Volume
LIPIcs, Volume 2
IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science
Event
FSTTCS 2008, December 9-11, 2008, Bangalore, IndiaEditors
Publication Details
- published at: 2008-12-05
- Publisher: Schloss Dagstuhl – Leibniz-Zentrum für Informatik
- ISBN: 978-3-939897-08-8
- DBLP: db/conf/fsttcs/fsttcs2008
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Document
Complete Volume
LIPIcs, Volume 2, FSTTCS'08, Complete Volume
Abstract
LIPIcs, Volume 2, FSTTCS'08, Complete Volume
Cite as
IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2013)
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@Proceedings{hariharan_et_al:LIPIcs.FSTTCS.2008,
title = {{LIPIcs, Volume 2, FSTTCS'08, Complete Volume}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2013},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008},
URN = {urn:nbn:de:0030-drops-40966},
doi = {10.4230/LIPIcs.FSTTCS.2008},
annote = {Keywords: LIPIcs, Volume 2, FSTTCS'08, Complete Volume}
}
Document
Front Matter
2008 Abstracts Collection -- IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science
Abstract
This volume contains the proceedings of the 28th international conference on the Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2008), organized under the auspices of the Indian Association for Research in Computing Science (IARCS).
Cite as
IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. i-xviii, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{hariharan_et_al:LIPIcs.FSTTCS.2008.1772,
author = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
title = {{2008 Abstracts Collection -- IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {i--xviii},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1772},
URN = {urn:nbn:de:0030-drops-17720},
doi = {10.4230/LIPIcs.FSTTCS.2008.1772},
annote = {Keywords: }
}
Document
2008 Preface -- IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science
Abstract
This volume contains the proceedings of the 28th international conference on the Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2008), organized under the auspices of the Indian Association for Research in Computing Science (IARCS). This year's conference attracted 117 submissions. Each submission was reviewed by at least three independent referees. The final selection of the papers making up the programme was done through an electronic discussion on EasyChair, spanning two weeks, without a physical meeting of the Programme Committee (PC). All PC members participated actively in the discussion.
We have five invited speakers this year: Hubert Comon-Lundh, Uriel Feige, Erich
Graedel, Simon Peyton Jones and Leslie Valiant. We thank them for having readily accepted our invitation to talk at the conference and for providing abstracts (and even full papers) for the proceedings.
We thank all the reviewers and PC members, without whose dedicated effort the conference would not be possible. We thank the Organizing Committee for making the arrangements for the conference. This year, the conference is being held at the Indian Institute of Science, Bangalore, as part of its centenary year celebrations. It is a great honour and privilege for the conference
to be recognized and associated with the institute on this occasion.
Finally, this year we have taken a decisive step in democratizing the conference by moving away from commercial publishers. Instead, we will be hosting the proceedings online, electronically, via the Dagstuhl Research Online Publication Server (DROPS). A complete copy of the proceedings will also be hosted on the FSTTCS website (www.fsttcs.org). The copyrights to the papers will reside not with the publishers but with the respective authors. The copyright is now governed by the Creative Commons attribution NC-ND.
We do hope this direction will be sustained in the future.
Cite as
Ramesh Hariharan, Madhavan Mukund, and V Vinay. 2008 Preface -- IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, p. -1, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{hariharan_et_al:LIPIcs.FSTTCS.2008.1771,
author = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
title = {{2008 Preface -- IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {-1---1},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1771},
URN = {urn:nbn:de:0030-drops-17713},
doi = {10.4230/LIPIcs.FSTTCS.2008.1771},
annote = {Keywords: Preface}
}
Document
3-connected Planar Graph Isomorphism is in Log-space
Abstract
We consider the isomorphism and canonization
problem for $3$-connected planar graphs. The
problem was known to be \Log-hard and in \ULcoUL\ \cite{TW07}. In this
paper, we give a deterministic log-space algorithm for $3$-connected
planar graph isomorphism and canonization.
This gives an \Log-completeness result,
thereby settling its complexity.
\par The algorithm uses the notion of universal exploration sequences
from \cite{koucky01} and \cite{Rei05}. To our knowledge, this is a
completely new approach to graph canonization.
Cite as
Samir Datta, Nutan Limaye, and Prajakta Nimbhorkar. 3-connected Planar Graph Isomorphism is in Log-space. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 155-162, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{datta_et_al:LIPIcs.FSTTCS.2008.1749,
author = {Datta, Samir and Limaye, Nutan and Nimbhorkar, Prajakta},
title = {{3-connected Planar Graph Isomorphism is in Log-space}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {155--162},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1749},
URN = {urn:nbn:de:0030-drops-17491},
doi = {10.4230/LIPIcs.FSTTCS.2008.1749},
annote = {Keywords: Planar graph isomorphism, three connected graphs, logspace, universal exploration sequence}
}
Document
A Cubic-Vertex Kernel for Flip Consensus Tree
Abstract
Given a bipartite graph G=(V_c,V_t,E) and a non-negative integer k, the NP-complete Minimum-Flip Consensus Tree problem asks whether G can be transformed, using up to k edge insertions and deletions, into a graph that does not contain an induced P_5 with its first vertex in V_t (a so-called M-graph or Sigma-graph). This problem plays an important role in computational phylogenetics, V_c standing for the characters and V_t standing for taxa. Chen et al. [IEEE/ACM TCBB 2006] showed that Minimum-Flip Consensus Tree is NP-complete and presented a parameterized algorithm with running time O(6^k\cdot |V_t|\cdot |V_c|).
Recently, Boecker et al. [IWPEC'08] presented a refined search tree algorithm
with running time O(4.83^k(|V_t|+|V_c|) + |V_t|\cdot |V_c|).
We complement these results by polynomial-time executable data reduction rules yielding a problem kernel with O(k^3) vertices.
Cite as
Christian Komusiewicz and Johannes Uhlmann. A Cubic-Vertex Kernel for Flip Consensus Tree. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 280-291, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{komusiewicz_et_al:LIPIcs.FSTTCS.2008.1760,
author = {Komusiewicz, Christian and Uhlmann, Johannes},
title = {{A Cubic-Vertex Kernel for Flip Consensus Tree}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {280--291},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1760},
URN = {urn:nbn:de:0030-drops-17600},
doi = {10.4230/LIPIcs.FSTTCS.2008.1760},
annote = {Keywords: Fixed-parameter algorithm, problem kernel, NP-hard problem, graph modification problem, computational phylogenetics}
}
Document
A Hierarchy of Semantics for Non-deterministic Term Rewriting Systems
Abstract
Formalisms involving some degree of nondeterminism are frequent in computer science. In particular, various programming or specification languages are based on term rewriting systems where confluence is not required. In this paper we examine three concrete possible semantics for non-determinism that can be assigned to those programs. Two of them --call-time choice and run-time choice-- are quite well-known, while the third one --plural semantics-- is investigated for the first time in the context of term rewriting based programming languages. We investigate some basic intrinsic properties of the semantics and establish some relationships between them: we show that the three semantics form a hierarchy in the sense of set inclusion, and we prove that call-time choice and plural semantics enjoy a remarkable compositionality property that fails for run-time choice; finally, we show how to express plural semantics within run-time choice by means of a program transformation, for which we prove its adequacy.
Cite as
Juan Rodriguez-Hortala. A Hierarchy of Semantics for Non-deterministic Term Rewriting Systems. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 328-339, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{rodriguezhortala:LIPIcs.FSTTCS.2008.1764,
author = {Rodriguez-Hortala, Juan},
title = {{A Hierarchy of Semantics for Non-deterministic Term Rewriting Systems}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {328--339},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1764},
URN = {urn:nbn:de:0030-drops-17643},
doi = {10.4230/LIPIcs.FSTTCS.2008.1764},
annote = {Keywords: Functional-logic programming, term rewriting systems, constructor-based rewriting logic, non-determinism, call-time choice semantics, run-time choice}
}
Document
A new approach to the planted clique problem
Abstract
We study the problem of finding a large planted clique in the random graph
$G_{n,1/2}$.
We reduce the problem to that of maximising a three dimensional tensor
over the unit ball
in $n$ dimensions. This latter problem has not been well studied and so we
hope that
this reduction will eventually lead to an improved solution to the planted
clique problem.
Cite as
Alan Frieze and Ravi Kannan. A new approach to the planted clique problem. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 187-198, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{frieze_et_al:LIPIcs.FSTTCS.2008.1752,
author = {Frieze, Alan and Kannan, Ravi},
title = {{A new approach to the planted clique problem}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {187--198},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1752},
URN = {urn:nbn:de:0030-drops-17521},
doi = {10.4230/LIPIcs.FSTTCS.2008.1752},
annote = {Keywords: Planted Clique, Tensor, Random Graph}
}
Document
A new upper bound for 3-SAT
Abstract
We show that a randomly chosen
$3$-CNF formula over $n$ variables with clauses-to-variables
ratio at least $4.4898$ is asymptotically almost surely unsatisfiable.
The previous best such bound,
due to Dubois in 1999, was $4.506$.
The first such bound, independently
discovered by many groups of researchers since 1983,
was $5.19$. Several decreasing values between
$5.19$ and $4.506$ were published in the years between.
The probabilistic techniques we use for the proof are, we believe, of independent interest.
Cite as
Josep Diaz, Lefteris Kirousis, Dieter Mitsche, and Xavier Perez-Gimenez. A new upper bound for 3-SAT. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 163-174, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{diaz_et_al:LIPIcs.FSTTCS.2008.1750,
author = {Diaz, Josep and Kirousis, Lefteris and Mitsche, Dieter and Perez-Gimenez, Xavier},
title = {{A new upper bound for 3-SAT}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {163--174},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1750},
URN = {urn:nbn:de:0030-drops-17507},
doi = {10.4230/LIPIcs.FSTTCS.2008.1750},
annote = {Keywords: Satisfiability, 3-SAT, random, threshold}
}
Document
About models of security protocols
Abstract
In this paper, mostly consisting of definitions, we revisit the models
of security protocols: we show that the symbolic and the computational
models (as well as others) are instances of a same generic model. Our
definitions are also parametrized by the security primitives, the
notion of attacker and, to some extent, the process calculus.
Cite as
Hubert Comon-Lundh. About models of security protocols. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 352-356, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{comonlundh:LIPIcs.FSTTCS.2008.1766,
author = {Comon-Lundh, Hubert},
title = {{About models of security protocols}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {352--356},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1766},
URN = {urn:nbn:de:0030-drops-17662},
doi = {10.4230/LIPIcs.FSTTCS.2008.1766},
annote = {Keywords: Protocols, security, concurrency, formal methods}
}
Document
Abstraction Refinement for Games with Incomplete Information
Abstract
Counterexample-guided abstraction refinement (CEGAR) is used in
automated software analysis to find suitable finite-state abstractions
of infinite-state systems. In this paper, we extend CEGAR to games
with incomplete information, as they commonly occur in controller
synthesis and modular verification. The challenge is that, under
incomplete information, one must carefully account for the knowledge
available to the player: the strategy must not depend on information
the player cannot see. We propose an abstraction mechanism for games under
incomplete information that incorporates the approximation of the players\' moves
into a knowledge-based subset construction on the abstract state
space. This abstraction results in a perfect-information game over a
finite graph. The concretizability of abstract strategies can be encoded as
the satisfiability of strategy-tree formulas. Based on this encoding,
we present an interpolation-based approach for selecting new predicates
and provide sufficient conditions for the termination of the resulting
refinement loop.
Cite as
Rayna Dimitrova and Bernd Finkbeiner. Abstraction Refinement for Games with Incomplete Information. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 175-186, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{dimitrova_et_al:LIPIcs.FSTTCS.2008.1751,
author = {Dimitrova, Rayna and Finkbeiner, Bernd},
title = {{Abstraction Refinement for Games with Incomplete Information}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {175--186},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1751},
URN = {urn:nbn:de:0030-drops-17510},
doi = {10.4230/LIPIcs.FSTTCS.2008.1751},
annote = {Keywords: Automatic abstraction refinement, synthesis}
}
Document
Algorithms for Game Metrics
Abstract
Simulation and bisimulation metrics for stochastic systems provide a
quantitative generalization of the classical simulation and
bisimulation relations.
These metrics capture the similarity of states with respect to
quantitative specifications written in the quantitative $\mu$-calculus
and related probabilistic logics.
We present algorithms for computing the metrics on Markov
decision processes (MDPs), turn-based stochastic games, and concurrent
games.
For turn-based games and MDPs, we provide a polynomial-time algorithm
based on linear programming
for the computation of the one-step metric distance between states.
The algorithm improves on the
previously known exponential-time algorithm based on a reduction to the theory of
reals.
We then present PSPACE algorithms for both the decision problem and the
problem of approximating the metric distance between two states,
matching the best known bound for Markov chains.
For the bisimulation kernel of the metric, which corresponds to probabilistic
bisimulation, our algorithm works in time $\calo(n^4)$ for both
turn-based games and MDPs; improving the previously best known
$\calo(n^9\cdot\log(n))$ time algorithm for MDPs.
For a concurrent game $G$, we show that computing the exact distance
between states is at least as hard as computing the value of
concurrent reachability games and
the square-root-sum problem in computational geometry.
We show that checking whether the metric distance is bounded by a
rational $r$, can be accomplished via a reduction to the theory of
real closed fields, involving a formula with three quantifier
alternations, yielding $\calo(|G|^{\calo(|G|^5)})$ time
complexity, improving the previously known reduction with
$\calo(|G|^{\calo(|G|^7)})$ time complexity.
These algorithms can be iterated to approximate the metrics using
binary search.
Cite as
Krishnendu Chatterjee, Luca de Alfaro, Rupak Majumdar, and Vishwanath Raman. Algorithms for Game Metrics. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 107-118, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{chatterjee_et_al:LIPIcs.FSTTCS.2008.1745,
author = {Chatterjee, Krishnendu and de Alfaro, Luca and Majumdar, Rupak and Raman, Vishwanath},
title = {{Algorithms for Game Metrics}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {107--118},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1745},
URN = {urn:nbn:de:0030-drops-17455},
doi = {10.4230/LIPIcs.FSTTCS.2008.1745},
annote = {Keywords: Algorithms, Metrics, Kernel, Simulation, Bisimulation, Linear Programming, Theory of Reals}
}
Document
All-Norms and All-L_p-Norms Approximation Algorithms
Abstract
In many optimization problems, a solution can be viewed as ascribing
a ``cost\'\' to each client, and the goal is to optimize some
aggregation of the per-client costs. We often optimize some
$L_p$-norm (or some other symmetric convex function or norm) of the
vector of costs---though different applications may suggest
different norms to use. Ideally, we could obtain a solution that
optimizes several norms simultaneously.
In this paper, we examine approximation algorithms that
simultaneously perform well on all norms, or on all $L_p$ norms.
A natural problem in this framework is the $L_p$ Set Cover
problem, which generalizes \textsc{Set Cover} and \textsc{Min-Sum Set
Cover}. We show that the greedy algorithm \emph{simultaneously
gives a $(p + \ln p + O(1))$-approximation for all $p$, and show
that this approximation ratio is optimal up to constants} under
reasonable complexity-theoretic assumptions.
We additionally show how to use our analysis techniques
to give similar results for the more general \emph{submodular set
cover}, and prove some results for the so-called \emph{pipelined set
cover} problem.
We then go on to examine approximation algorithms in the
``all-norms\'\' and the ``all-$L_p$-norms\'\' frameworks more broadly,
and present algorithms and structural results for other problems
such as $k$-facility-location, TSP, and average flow-time
minimization, extending and unifying previously
known results.
Cite as
Daniel Golovin, Anupam Gupta, Amit Kumar, and Kanat Tangwongsan. All-Norms and All-L_p-Norms Approximation Algorithms. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 199-210, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{golovin_et_al:LIPIcs.FSTTCS.2008.1753,
author = {Golovin, Daniel and Gupta, Anupam and Kumar, Amit and Tangwongsan, Kanat},
title = {{All-Norms and All-L\underlinep-Norms Approximation Algorithms}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {199--210},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1753},
URN = {urn:nbn:de:0030-drops-17537},
doi = {10.4230/LIPIcs.FSTTCS.2008.1753},
annote = {Keywords: Approximation algorithms, set-cover problems, combinatorial optimization, sampling minkowski norms}
}
Document
An Optimal Construction of Finite Automata from Regular Expressions
Abstract
We consider the construction of finite automata from their corresponding regular expressions by a series of digraph-transformations along the expression\'s structure.
Each intermediate graph represents an extended finite automaton accepting the same language. The character of our construction allows a fine-grained analysis of the
emerging automaton\'s size, eventually leading to an optimality result.
Cite as
Stefan Gulan and Henning Fernau. An Optimal Construction of Finite Automata from Regular Expressions. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 211-222, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{gulan_et_al:LIPIcs.FSTTCS.2008.1754,
author = {Gulan, Stefan and Fernau, Henning},
title = {{An Optimal Construction of Finite Automata from Regular Expressions}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {211--222},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1754},
URN = {urn:nbn:de:0030-drops-17544},
doi = {10.4230/LIPIcs.FSTTCS.2008.1754},
annote = {Keywords: Finite automata,regular expressions,descriptional complexity}
}
Document
Analyzing Asynchronous Programs with Preemption
Abstract
Multiset pushdown systems have been introduced by Sen and
Viswanathan as an adequate model for asynchronous programs where
some procedure calls can be stored as tasks to be processed
later. The model is a pushdown system supplied with a multiset of
pending tasks. Tasks may be added to the multiset at each
transition, whereas a task is taken from the multiset only when
the stack is empty. In this paper, we consider an extension of
these models where tasks may be of different priority level, and
can be preempted at any point of their execution by tasks of
higher priority. We investigate the control point reachability
problem for these models. Our main result is that this problem is
decidable by reduction to the reachability problem for a
decidable class of Petri nets with inhibitor arcs. We also
identify two subclasses of these models for which the control
point reachability problem is reducible respectively to the
reachability problem and to the coverability problem for Petri
nets (without inhibitor arcs).
Cite as
Mohamed Faouzi Atig, Ahmed Bouajjani, and Tayssir Touili. Analyzing Asynchronous Programs with Preemption. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 37-48, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{atig_et_al:LIPIcs.FSTTCS.2008.1739,
author = {Atig, Mohamed Faouzi and Bouajjani, Ahmed and Touili, Tayssir},
title = {{Analyzing Asynchronous Programs with Preemption}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {37--48},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1739},
URN = {urn:nbn:de:0030-drops-17398},
doi = {10.4230/LIPIcs.FSTTCS.2008.1739},
annote = {Keywords: Multiset Pushdown Systems, Multithreaded Asynchronous Programs, Program verification, Verification algorithms}
}
Document
Analyzing the Implicit Computational Complexity of object-oriented programs
Abstract
A sup-interpretation is a tool which provides upper bounds on the size of the values computed by the function symbols of a program. Sup-interpretations have shown their interest to deal with the complexity of first order functional programs. This paper is an attempt to adapt the framework of sup-interpretations to a fragment of object-oriented programs, including loop and while constructs and methods with side effects.
We give a criterion, called brotherly criterion, which uses the notion of sup-interpretation to ensure that each brotherly program computes objects whose size is polynomially bounded by the inputs sizes. Moreover we give some heuristics in order to compute the sup-interpretation of a given method.
Cite as
Jean-Yves Marion and Romain Pechoux. Analyzing the Implicit Computational Complexity of object-oriented programs. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 316-327, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{marion_et_al:LIPIcs.FSTTCS.2008.1763,
author = {Marion, Jean-Yves and Pechoux, Romain},
title = {{Analyzing the Implicit Computational Complexity of object-oriented programs}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {316--327},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1763},
URN = {urn:nbn:de:0030-drops-17638},
doi = {10.4230/LIPIcs.FSTTCS.2008.1763},
annote = {Keywords: Implicit computational complexity, object-oriented programs, sup-interpretation, resource upper bounds}
}
Document
Average-Time Games
Abstract
An average-time game is played on the infinite graph of
configurations of a finite timed automaton.
The two players, Min and Max, construct an infinite run of the
automaton by taking turns to perform a timed transition.
Player Min wants to minimize the average time per transition and
player Max wants to maximize it.
A solution of average-time games is presented using a reduction to
average-price game on a finite graph.
A direct consequence is an elementary proof of determinacy for
average-time games.
This complements our results for reachability-time games and
partially solves a problem posed by Bouyer et al., to design an
algorithm for solving average-price games on priced timed
automata.
The paper also establishes the exact computational complexity of
solving average-time games: the problem is EXPTIME-complete for
timed automata with at least two clocks.
Cite as
Marcin Jurdzinski and Ashutosh Trivedi. Average-Time Games. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 340-351, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{jurdzinski_et_al:LIPIcs.FSTTCS.2008.1765,
author = {Jurdzinski, Marcin and Trivedi, Ashutosh},
title = {{Average-Time Games}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {340--351},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1765},
URN = {urn:nbn:de:0030-drops-17650},
doi = {10.4230/LIPIcs.FSTTCS.2008.1765},
annote = {Keywords: Games on Timed Automata, Mean-payoff Games, Average-Time Games, Game Theory}
}
Document
Banach-Mazur Games on Graphs
Abstract
We survey determinacy, definability, and
complexity issues of Banach-Mazur games on finite and
infinite graphs.
Infinite games where two players take turns to move a token
through a directed graph, thus tracing out an infinite path,
have numerous applications in different branches of mathematics
and computer science. In the usual format,
the possible moves of the players are given by
the edges of the graph; in each move
a player takes the token from its current position
along an edge to a next position. In Banach-Mazur games
the players instead select in each move a \emph{path}
of arbitrary finite length rather than just an edge.
In both cases the outcome of a play is an infinite
path. A winning condition is thus given by a set of
infinite paths which is often specified by a logical formula,
for instance from S1S, LTL, or first-order logic.
Banach-Mazur games have a long tradition in descriptive
set theory and topology, and they have recently been shown to
have interesting applications also in computer science,
for instance for planning in nondeterministic domains,
for the study of fairness in concurrent systems, and
for the semantics of timed automata.
It turns out that Banach-Mazur games behave quite differently than
the usual graph games. Often they admit simpler winning strategies
and more efficient algorithmic solutions. For instance, Banach-Mazur
games with $\omega$-regular winning conditions always have
positional winning strategies, and winning positions
for finite Banach-Mazur games with Muller winning condition
are computable in polynomial time.
Cite as
Erich Graedel. Banach-Mazur Games on Graphs. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 364-382, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{graedel:LIPIcs.FSTTCS.2008.1768,
author = {Graedel, Erich},
title = {{Banach-Mazur Games on Graphs}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {364--382},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1768},
URN = {urn:nbn:de:0030-drops-17684},
doi = {10.4230/LIPIcs.FSTTCS.2008.1768},
annote = {Keywords: Games, strategies, determinacy, positional determinacy, definability, complexity}
}
Document
Boolean algebras of unambiguous context-free languages
Abstract
Several recent works have studied subfamilies of deterministic
context-free languages with good closure properties, for instance
the families of input-driven or visibly pushdown languages, or more
generally families of languages accepted by pushdown automata whose
stack height can be uniquely determined by the input word read so
far. These ideas can be described as a notion of synchronization.
In this paper we present an extension of synchronization to all
context-free languages using graph grammars. This generalization
allows one to define boolean algebras of non-deterministic but
unambiguous context-free languages containing regular languages.
Cite as
Didier Caucal. Boolean algebras of unambiguous context-free languages. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 83-94, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{caucal:LIPIcs.FSTTCS.2008.1743,
author = {Caucal, Didier},
title = {{Boolean algebras of unambiguous context-free languages}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {83--94},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1743},
URN = {urn:nbn:de:0030-drops-17436},
doi = {10.4230/LIPIcs.FSTTCS.2008.1743},
annote = {Keywords: Synchronization, deterministic graph grammars}
}
Document
Complexity Analysis of Term Rewriting Based on Matrix and Context Dependent Interpretations
Abstract
For a given (terminating) term rewriting system
one can often estimate its \emph{derivational complexity} indirectly
by looking at the proof method that established termination. In this
spirit we investigate two instances of the interpretation method:
\emph{matrix interpretations} and \emph{context dependent interpretations}.
We introduce a subclass of matrix interpretations, denoted
as \emph{triangular matrix interpretations}, which induce
polynomial derivational complexity and establish tight correspondence
results between a subclass of context dependent interpretations and
restricted triangular matrix interpretations.
The thus obtained new results are easy to implement and
considerably extend the analytic power of existing results.
We provide ample numerical data for assessing the viability of the method.
Cite as
Georg Moser, Andreas Schnabl, and Johannes Waldmann. Complexity Analysis of Term Rewriting Based on Matrix and Context Dependent Interpretations. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 304-315, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{moser_et_al:LIPIcs.FSTTCS.2008.1762,
author = {Moser, Georg and Schnabl, Andreas and Waldmann, Johannes},
title = {{Complexity Analysis of Term Rewriting Based on Matrix and Context Dependent Interpretations}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {304--315},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1762},
URN = {urn:nbn:de:0030-drops-17626},
doi = {10.4230/LIPIcs.FSTTCS.2008.1762},
annote = {Keywords: Term Rewriting, Derivational Complexity, Termination, Automation}
}
Document
Dynamic matrix rank with partial lookahead
Abstract
We consider the problem of maintaining information about the
rank of a matrix $M$ under changes to its entries. For an $n \times n$ matrix $M$,
we show an amortized upper
bound of $O(n^{\omega-1})$ arithmetic operations per change for
this problem, where $\omega < 2.376$ is the exponent for matrix
multiplication, under the assumption that there is a {\em lookahead}
of up to $\Theta(n)$ locations. That is, we know up to the next $\Theta(n)$
locations $(i_1,j_1),(i_2,j_2),\ldots,$ whose entries
are going to change, in advance; however we do not know the new entries
in these locations in advance. We get the new entries in these
locations in a dynamic manner.
Cite as
Telikepalli Kavitha. Dynamic matrix rank with partial lookahead. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 268-279, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{kavitha:LIPIcs.FSTTCS.2008.1759,
author = {Kavitha, Telikepalli},
title = {{Dynamic matrix rank with partial lookahead}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {268--279},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1759},
URN = {urn:nbn:de:0030-drops-17594},
doi = {10.4230/LIPIcs.FSTTCS.2008.1759},
annote = {Keywords: Matrix rank, dynamic algorithm, fast matrix multiplication}
}
Document
Explicit Muller Games are PTIME
Abstract
Regular games provide a very useful model for the synthesis of controllers in reactive systems. The complexity of these games depends on the representation of the winning condition: if it is represented through a win-set, a coloured condition, a Zielonka-DAG or Emerson-Lei formulae, the winner problem is \pspace-complete; if the winning condition is represented as a Zielonka tree, the winner problem belongs to \np and \conp. In this paper, we show that explicit Muller games can be solved in polynomial time, and provide an effective algorithm to compute the winning regions.
Cite as
Florian Horn. Explicit Muller Games are PTIME. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 235-243, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{horn:LIPIcs.FSTTCS.2008.1756,
author = {Horn, Florian},
title = {{Explicit Muller Games are PTIME}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {235--243},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1756},
URN = {urn:nbn:de:0030-drops-17565},
doi = {10.4230/LIPIcs.FSTTCS.2008.1756},
annote = {Keywords: Games, authomata, model checking}
}
Document
Graph Games on Ordinals
Abstract
We consider an extension of Church\'s synthesis problem to ordinals by adding
limit transitions to graph games. We consider game arenas where these limit
transitions are defined using the sets of cofinal states. In a
previous paper, we have shown that such games of ordinal length are determined
and that the winner problem is \pspace-complete, for a subclass of arenas
where the length of plays is always smaller than $\omega^\omega$. However,
the proof uses a rather involved reduction to classical Muller games, and the
resulting strategies need infinite memory.
We adapt the LAR reduction to prove the determinacy in the general case, and
to generate strategies with finite memory, using a reduction to games where
the limit transitions are defined by priorities. We provide an algorithm for
computing the winning regions of both players in these games, with a
complexity similar to parity games. Its analysis yields three results:
determinacy without hypothesis on the length of the plays, existence of
memoryless strategies, and membership of the winner problem in \npconp.
Cite as
Julien Cristau and Florian Horn. Graph Games on Ordinals. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 143-154, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{cristau_et_al:LIPIcs.FSTTCS.2008.1748,
author = {Cristau, Julien and Horn, Florian},
title = {{Graph Games on Ordinals}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {143--154},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1748},
URN = {urn:nbn:de:0030-drops-17485},
doi = {10.4230/LIPIcs.FSTTCS.2008.1748},
annote = {Keywords: Games, ordinals, zeno}
}
Document
Harnessing the Multicores: Nested Data Parallelism in Haskell
Abstract
If you want to program a parallel computer, a purely functional
language like Haskell is a promising starting point. Since the
language is pure, it is by-default safe for parallel evaluation,
whereas imperative languages are by-default unsafe. But that doesn\'t
make it easy! Indeed it has proved quite difficult to get robust,
scalable performance increases through parallel functional
programming, especially as the number of processors increases.
A particularly promising and well-studied approach to employing large
numbers of processors is data parallelism. Blelloch\'s
pioneering work on NESL showed that it was possible to combine a
rather flexible programming model (nested data parallelism) with a
fast, scalable execution model (flat data parallelism). In this paper
we describe Data Parallel Haskell, which embodies nested data
parallelism in a modern, general-purpose language, implemented in a
state-of-the-art compiler, GHC. We focus particularly on the
vectorisation transformation, which transforms nested to flat data
parallelism.
Cite as
Simon Peyton Jones, Roman Leshchinskiy, Gabriele Keller, and Manuel M T Chakravarty. Harnessing the Multicores: Nested Data Parallelism in Haskell. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 383-414, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{peytonjones_et_al:LIPIcs.FSTTCS.2008.1769,
author = {Peyton Jones, Simon and Leshchinskiy, Roman and Keller, Gabriele and Chakravarty, Manuel M T},
title = {{Harnessing the Multicores: Nested Data Parallelism in Haskell}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {383--414},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1769},
URN = {urn:nbn:de:0030-drops-17697},
doi = {10.4230/LIPIcs.FSTTCS.2008.1769},
annote = {Keywords: Nested data parallelism, Vectorisation, Haskell, Program transformation}
}
Document
Extended Abstract
Implicit Branching and Parameterized Partial Cover Problems (Extended Abstract)
Abstract
Covering problems are fundamental
classical problems in optimization, computer science and complexity
theory. Typically an input to these problems is a family of sets over
a finite universe and the goal is to cover the elements of the
universe with as few sets of the family as possible.
The variations of covering problems
include well known problems like Set Cover, Vertex Cover,
Dominating Set and Facility Location to name a few. Recently
there has been a lot of study on partial covering problems, a
natural generalization of covering problems. Here, the goal is not to
cover all the elements but to cover the specified number of
elements with the minimum number of sets.
Cite as
Omid Amini, Fedor Fomin, and Saket Saurabh. Implicit Branching and Parameterized Partial Cover Problems (Extended Abstract). In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 1-12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{amini_et_al:LIPIcs.FSTTCS.2008.1736,
author = {Amini, Omid and Fomin, Fedor and Saurabh, Saket},
title = {{Implicit Branching and Parameterized Partial Cover Problems}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {1--12},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1736},
URN = {urn:nbn:de:0030-drops-17363},
doi = {10.4230/LIPIcs.FSTTCS.2008.1736},
annote = {Keywords: Implicit Branching, Parameterized Algorithms, Partial Dominating Set, Partial Vertex Cover, Local Treewidth}
}
Document
Increasing the power of the verifier in Quantum Zero Knowledge
Abstract
In quantum zero knowledge, the assumption was made that the
verifier is only using unitary operations. Under this assumption,
many nice properties have been shown about quantum zero
knowledge, including the fact that Honest-Verifier Quantum
Statistical Zero Knowledge ($HVQSZK$) is equal to
Cheating-Verifier Quantum Statistical Zero Knowledge ($QSZK$)
(see ~\cite{Wat02,Wat06}).
In this paper, we study what happens when we allow an honest
verifier to flip some coins in addition to using unitary
operations. Flipping a coin is a non-unitary operation but
doesn\'t seem at first to enhance the cheating possibilities of
the verifier since a classical honest verifier can flip coins. In
this setting, we show an unexpected result: any classical
Interactive Proof has an Honest-Verifier Quantum Statistical Zero
Knowledge proof with coins. Note that in the classical case,
honest verifier $SZK$ is no more powerful than $SZK$ and hence it
is not believed to contain even $NP$. On the other hand, in the
case of cheating verifiers, we show that Quantum Statistical Zero
Knowledge where the verifier applies any non-unitary operation is
equal to Quantum Zero-Knowledge where the verifier uses only
unitaries.
One can think of our results in two complementary ways. If we
would like to use the honest verifier model as a means to study
the general model by taking advantage of their equivalence, then
it is imperative to use the unitary definition without coins,
since with the general one this equivalence is most probably not
true. On the other hand, if we would like to use quantum zero
knowledge protocols in a cryptographic scenario where the
honest-but-curious model is sufficient, then adding the unitary
constraint severely decreases the power of quantum zero knowledge
protocols.
Cite as
Andre Chailloux and Iordanis Kerenidis. Increasing the power of the verifier in Quantum Zero Knowledge. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 95-106, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{chailloux_et_al:LIPIcs.FSTTCS.2008.1744,
author = {Chailloux, Andre and Kerenidis, Iordanis},
title = {{Increasing the power of the verifier in Quantum Zero Knowledge}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {95--106},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1744},
URN = {urn:nbn:de:0030-drops-17446},
doi = {10.4230/LIPIcs.FSTTCS.2008.1744},
annote = {Keywords: Quantum cryptography, zero-knowledge protocols, honest-verifier, quantum semi-honest model, hiddenquantum cryptography, zero-knowledge protocols, honest-verifier, quantum semi-honest model, hidden-bits}
}
Document
Knowledge Infusion: In Pursuit of Robustness in Artificial Intelligence
Abstract
Endowing computers with the ability to apply commonsense
knowledge with human-level performance is a primary challenge for
computer science, comparable in importance to past great
challenges in other fields of science such as the sequencing of the
human genome. The right approach to this problem is still under
debate. Here we shall discuss and attempt to justify one approach,
that of {\it knowledge infusion}. This approach is based on the view that
the fundamental objective that needs to be achieved is {\it robustness} in the following sense: a
framework is needed in which a computer system can represent pieces of
knowledge about the world, each piece having some uncertainty, and the
interactions among the pieces having even more uncertainty, such that
the system can nevertheless reason from these pieces so that the
uncertainties in its conclusions are at least controlled. In knowledge
infusion rules are learned from the world in a principled way so that
subsequent reasoning using these rules will also be principled, and
subject only to errors that can be bounded in terms of the inverse of the effort
invested in the learning process.
Cite as
Leslie G Valiant. Knowledge Infusion: In Pursuit of Robustness in Artificial Intelligence. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 415-422, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{valiant:LIPIcs.FSTTCS.2008.1770,
author = {Valiant, Leslie G},
title = {{Knowledge Infusion: In Pursuit of Robustness in Artificial Intelligence}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {415--422},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1770},
URN = {urn:nbn:de:0030-drops-17703},
doi = {10.4230/LIPIcs.FSTTCS.2008.1770},
annote = {Keywords: Artificial intelligence, knowledge acquisition, knowledge representation,learning, reasoning, robustness}
}
Document
Leaf languages and string compression
Abstract
Tight connections between leafs languages and strings compressed
via straight-line programs (SLPs) are established. It is shown
that the compressed membership problem for a language $L$ is complete
for the leaf language class defined by $L$ via logspace machines.
A more difficult variant of the compressed membership problem for
$L$ is shown to be complete for the leaf language class defined
by $L$ via polynomial time machines. As a corollary,
a fixed linear visibly pushdown language with
a PSPACE-complete compressed membership problem is obtained.
For XML languages,
the compressed membership problem is shown to be coNP-complete.
Cite as
Markus Lohrey. Leaf languages and string compression. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 292-303, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{lohrey:LIPIcs.FSTTCS.2008.1761,
author = {Lohrey, Markus},
title = {{Leaf languages and string compression}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {292--303},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1761},
URN = {urn:nbn:de:0030-drops-17612},
doi = {10.4230/LIPIcs.FSTTCS.2008.1761},
annote = {Keywords: Leaf languages, string compression, grammar-based compression, complexity theory}
}
Document
On Estimation Algorithms vs Approximation Algorithms
Abstract
In a combinatorial optimization problem, when given an input
instance, one seeks a feasible solution that optimizes the value
of the objective function. Many combinatorial optimization
problems are NP-hard. A way of coping with NP-hardness is by
considering approximation algorithms. These algorithms run in
polynomial time, and their performance is measured by their
approximation ratio: the worst case ratio between the value of the
solution produced and the value of the (unknown) optimal solution.
In some cases the design of approximation algorithms includes a
nonconstructive component. As a result, the algorithms become
estimation algorithms rather than approximation algorithms: they
allow one to estimate the value of the optimal solution, without
actually producing a solution whose value is close to optimal.
We shall present a few such examples, and discuss some open
questions.
Cite as
Uriel Feige. On Estimation Algorithms vs Approximation Algorithms. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 357-363, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{feige:LIPIcs.FSTTCS.2008.1767,
author = {Feige, Uriel},
title = {{On Estimation Algorithms vs Approximation Algorithms}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {357--363},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1767},
URN = {urn:nbn:de:0030-drops-17676},
doi = {10.4230/LIPIcs.FSTTCS.2008.1767},
annote = {Keywords: Estimation Algorithms, Approximation Algorithms, Combinatorial Optimization}
}
Document
On the Power of Imperfect Information
Abstract
We present a polynomial-time reduction
from parity games with imperfect information to safety games with imperfect information.
Similar reductions for games with perfect information typically
increase the game size exponentially. Our construction
avoids such a blow-up by using imperfect information to realise
succinct counters which cover a range exponentially larger than their size.
In particular, the reduction shows that the problem of
solving imperfect-information games with safety conditions is
\EXPTIME-complete.
Cite as
Dietmar Berwanger and Laurent Doyen. On the Power of Imperfect Information. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 73-82, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{berwanger_et_al:LIPIcs.FSTTCS.2008.1742,
author = {Berwanger, Dietmar and Doyen, Laurent},
title = {{On the Power of Imperfect Information}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {73--82},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1742},
URN = {urn:nbn:de:0030-drops-17427},
doi = {10.4230/LIPIcs.FSTTCS.2008.1742},
annote = {Keywords: Infinite games, imperfect information}
}
Document
Pruning 2-Connected Graphs
Abstract
Given an edge-weighted undirected graph $G$ with a specified set of
terminals, let the \emph{density} of any subgraph be the ratio of
its weight/cost to the number of terminals it contains. If $G$ is
2-connected, does it contain smaller 2-connected subgraphs of
density comparable to that of $G$? We answer this question in the
affirmative by giving an algorithm to \emph{prune} $G$ and find such
subgraphs of any desired size, at the cost of only a logarithmic
increase in density (plus a small additive factor).
We apply the pruning techniques to give algorithms for two NP-Hard
problems on finding large 2-vertex-connected subgraphs of low cost;
no previous approximation algorithm was known for either problem. In
the \kv problem, we are given an undirected graph $G$ with edge
costs and an integer $k$; the goal is to find a minimum-cost
2-vertex-connected subgraph of $G$ containing at least $k$
vertices. In the \bv\ problem, we are given the graph $G$ with edge
costs, and a budget $B$; the goal is to find a 2-vertex-connected
subgraph $H$ of $G$ with total edge cost at most $B$ that maximizes
the number of vertices in $H$. We describe an $O(\log n \log k)$
approximation for the \kv problem, and a bicriteria approximation
for the \bv\ problem that gives an $O(\frac{1}{\eps}\log^2 n)$
approximation, while violating the budget by a factor of at most
$3+\eps$.
Cite as
Chandra Chekuri and Nitish Korula. Pruning 2-Connected Graphs. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 119-130, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{chekuri_et_al:LIPIcs.FSTTCS.2008.1746,
author = {Chekuri, Chandra and Korula, Nitish},
title = {{Pruning 2-Connected Graphs}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {119--130},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1746},
URN = {urn:nbn:de:0030-drops-17469},
doi = {10.4230/LIPIcs.FSTTCS.2008.1746},
annote = {Keywords: 2-Connected Graphs, k-MST, Density, Approximation}
}
Document
Runtime Monitoring of Metric First-order Temporal Properties
Abstract
We introduce a novel approach to the runtime monitoring of complex
system properties. In particular, we present an online algorithm for
a safety fragment of metric first-order temporal logic that
is considerably more expressive than the logics supported by prior
monitoring methods. Our approach, based on automatic structures,
allows the unrestricted use of negation, universal and existential
quantification over infinite domains, and the arbitrary nesting of
both past and bounded future operators. Moreover, we show how
to optimize our approach for the common case where
structures consist of only finite relations, over possibly infinite
domains. Under an additional restriction, we prove that the space
consumed by our monitor is polynomially bounded by the cardinality
of the data appearing in the processed prefix of the temporal
structure being monitored.
Cite as
David Basin, Felix Klaedtke, Samuel Müller, and Birgit Pfitzmann. Runtime Monitoring of Metric First-order Temporal Properties. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 49-60, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{basin_et_al:LIPIcs.FSTTCS.2008.1740,
author = {Basin, David and Klaedtke, Felix and M\"{u}ller, Samuel and Pfitzmann, Birgit},
title = {{Runtime Monitoring of Metric First-order Temporal Properties}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {49--60},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1740},
URN = {urn:nbn:de:0030-drops-17404},
doi = {10.4230/LIPIcs.FSTTCS.2008.1740},
annote = {Keywords: Runtime Monitoring, Metric First-order Temporal Logic, Automatic Structures, Temporal Databases}
}
Document
Single-Sink Network Design with Vertex Connectivity Requirements
Abstract
We study single-sink network design problems in undirected graphs
with vertex connectivity requirements. The input to these problems
is an edge-weighted undirected graph $G=(V,E)$, a sink/root vertex
$r$, a set of terminals $T \subseteq V$, and integer $k$. The goal is
to connect each terminal $t \in T$ to $r$ via $k$ \emph{vertex-disjoint}
paths. In the {\em connectivity} problem, the objective is to find a
min-cost subgraph of $G$ that contains the desired paths. There is a
$2$-approximation for this problem when $k \le 2$ \cite{FleischerJW}
but for $k \ge 3$, the first non-trivial approximation was obtained
in the recent work of Chakraborty, Chuzhoy and Khanna
\cite{ChakCK08}; they describe and analyze an algorithm with an
approximation ratio of $O(k^{O(k^2)}\log^4 n)$ where $n=|V|$.
In this paper, inspired by the results and ideas in \cite{ChakCK08},
we show an $O(k^{O(k)}\log |T|)$-approximation bound for a simple
greedy algorithm. Our analysis is based on the dual of a natural
linear program and is of independent technical interest. We use the
insights from this analysis to obtain an $O(k^{O(k)}\log
|T|)$-approximation for the more general single-sink {\em
rent-or-buy} network design problem with vertex connectivity
requirements. We further extend the ideas to obtain a
poly-logarithmic approximation for the single-sink {\em buy-at-bulk}
problem when $k=2$ and the number of cable-types is a fixed
constant; we believe that this should extend to any fixed $k$. We
also show that for the non-uniform buy-at-bulk problem, for each
fixed $k$, a small variant of a simple algorithm suggested by
Charikar and Kargiazova \cite{CharikarK05} for the case of $k=1$
gives an $2^{O(\sqrt{\log |T|})}$ approximation for larger $k$.
These results show that for each of these problems, simple and
natural algorithms that have been developed for $k=1$ have good
performance for small $k > 1$.
Cite as
Chandra Chekuri and Nitish Korula. Single-Sink Network Design with Vertex Connectivity Requirements. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 131-142, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{chekuri_et_al:LIPIcs.FSTTCS.2008.1747,
author = {Chekuri, Chandra and Korula, Nitish},
title = {{Single-Sink Network Design with Vertex Connectivity Requirements}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {131--142},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1747},
URN = {urn:nbn:de:0030-drops-17475},
doi = {10.4230/LIPIcs.FSTTCS.2008.1747},
annote = {Keywords: Network Design, Vertex Connectivity, Buy-at-Bulk, Rent-or-Buy, Approximation}
}
Document
Solvency Games
Abstract
We study the decision theory of a maximally risk-averse investor ---
one whose objective, in the face of stochastic uncertainties, is to
minimize the probability of ever going broke. With a view to
developing the mathematical basics of such a theory, we start with a
very simple model and obtain the following results: a characterization
of best play by investors; an explanation of why poor and rich players
may have different best strategies; an explanation of why
expectation-maximization is not necessarily the best strategy even for
rich players. For computation of optimal play, we show how to apply
the Value Iteration method, and prove a bound on its convergence
rate.
Cite as
Noam Berger, Nevin Kapur, Leonard Schulman, and Vijay Vazirani. Solvency Games. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 61-72, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{berger_et_al:LIPIcs.FSTTCS.2008.1741,
author = {Berger, Noam and Kapur, Nevin and Schulman, Leonard and Vazirani, Vijay},
title = {{Solvency Games}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {61--72},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1741},
URN = {urn:nbn:de:0030-drops-17419},
doi = {10.4230/LIPIcs.FSTTCS.2008.1741},
annote = {Keywords: Decision making under uncertainity, multi-arm bandit problems, game theory}
}
Document
Some Sieving Algorithms for Lattice Problems
Abstract
We study the algorithmic complexity of lattice problems based on the
sieving technique due to Ajtai, Kumar, and Sivakumar~\cite{aks}.
Given a $k$-dimensional subspace $M\subseteq \R^n$ and a full rank
integer lattice $\L\subseteq \Q^n$, the \emph{subspace avoiding
problem} SAP, defined by Bl\"omer and Naewe \cite{blomer}, is to
find a shortest vector in $\L\setminus M$. We first give a $2^{O(n+k
\log k)}$ time algorithm to solve \emph{the subspace avoiding
problem}. Applying this algorithm we obtain the following
results.
\begin{enumerate}
\item We give a $2^{O(n)}$ time algorithm to compute $i^{th}$
successive minima of a full rank lattice $\L\subset \Q^n$ if $i$ is
$O(\frac{n}{\log n})$.
\item We give a $2^{O(n)}$ time algorithm to solve a restricted
\emph{closest vector problem CVP} where the inputs fulfil a promise
about the distance of the input vector from the lattice.
\item We also show that unrestricted CVP has a $2^{O(n)}$ exact
algorithm if there is a $2^{O(n)}$ time exact algorithm for solving
CVP with additional input $v_i\in \L, 1\leq i\leq n$, where
$\|v_i\|_p$ is the $i^{th}$ successive minima of $\L$ for each $i$.
\end{enumerate}
We also give a new approximation algorithm for SAP and the
\emph{Convex Body Avoiding problem} which is a generalization of SAP.
Several of our algorithms work for \emph{gauge} functions as metric,
where the gauge function has a natural restriction and is accessed by
an oracle.
Cite as
V. Arvind and Pushkar S. Joglekar. Some Sieving Algorithms for Lattice Problems. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 25-36, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{arvind_et_al:LIPIcs.FSTTCS.2008.1738,
author = {Arvind, V. and Joglekar, Pushkar S.},
title = {{Some Sieving Algorithms for Lattice Problems}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {25--36},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1738},
URN = {urn:nbn:de:0030-drops-17380},
doi = {10.4230/LIPIcs.FSTTCS.2008.1738},
annote = {Keywords: Lattice problems, sieving algorithm, closest vector problem}
}
Document
Sound Lemma Generation for Proving Inductive Validity of Equations
Abstract
In many automated methods for proving inductive theorems, finding a
suitable generalization of a conjecture is a key for the success of
proof attempts. On the other hand, an obtained generalized conjecture
may not be a theorem, and in this case hopeless proof attempts for the
incorrect conjecture are made, which is against the success and
efficiency of theorem proving. Urso and Kounalis (2004) proposed a
generalization method for proving inductive validity of equations,
called sound generalization, that avoids such an over-generalization.
Their method guarantees that if the original conjecture is an
inductive theorem then so is the obtained generalization. In this
paper, we revise and extend their method. We restore a condition on
one of the characteristic argument positions imposed in their previous
paper and show that otherwise there exists a counterexample to their
main theorem. We also relax a condition imposed in their framework
and add some flexibilities to some of other characteristic argument
positions so as to enlarge the scope of the technique.
Cite as
Takahito Aoto. Sound Lemma Generation for Proving Inductive Validity of Equations. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 13-24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{aoto:LIPIcs.FSTTCS.2008.1737,
author = {Aoto, Takahito},
title = {{Sound Lemma Generation for Proving Inductive Validity of Equations}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {13--24},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1737},
URN = {urn:nbn:de:0030-drops-17379},
doi = {10.4230/LIPIcs.FSTTCS.2008.1737},
annote = {Keywords: Sound generalization, inductive theorem, automated theorem proving, term rewriting}
}
Document
STCON in Directed Unique-Path Graphs
Abstract
We study the problem of space-efficient
polynomial-time algorithms for {\em directed
st-connectivity} (STCON).
Given a directed graph $G$, and a pair of vertices $s, t$, the STCON problem
is to decide if there exists a path from $s$ to $t$ in $G$.
For general graphs, the best polynomial-time algorithm for STCON
uses space that is only slightly sublinear.
However, for special classes of directed graphs, polynomial-time poly-logarithmic-space
algorithms are known for STCON. In this paper, we continue this thread of research
and study a class of graphs called
\emph{unique-path graphs with respect to source $s$},
where there is at most one simple path from $s$ to any vertex in the graph.
For these graphs, we give
a polynomial-time algorithm that uses
$\tilde O(n^{\varepsilon})$ space for any constant $\varepsilon \in (0,1]$.
We also give a polynomial-time, $\tilde O(n^\varepsilon)$-space
algorithm to \emph{recognize} unique-path graphs.
Unique-path graphs are related to configuration graphs of unambiguous
log-space computations, but they can have some directed cycles. Our results
may be viewed along the continuum of sublinear-space polynomial-time
algorithms for STCON in different classes of directed graphs - from
slightly sublinear-space algorithms for general graphs to $O(\log n)$ space algorithms for trees.
Cite as
Sampath Kannan, Sanjeev Khanna, and Sudeepa Roy. STCON in Directed Unique-Path Graphs. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 256-267, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{kannan_et_al:LIPIcs.FSTTCS.2008.1758,
author = {Kannan, Sampath and Khanna, Sanjeev and Roy, Sudeepa},
title = {{STCON in Directed Unique-Path Graphs}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {256--267},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1758},
URN = {urn:nbn:de:0030-drops-17589},
doi = {10.4230/LIPIcs.FSTTCS.2008.1758},
annote = {Keywords: Algorithm, complexity, st-connectivity}
}
Document
The Complexity of Tree Transducer Output Languages
Abstract
Two complexity results are shown for the output languages
generated by compositions of macro tree transducers.
They are in $\NSPACE(n)$
and hence are context-sensitive,
and the class is NP-complete.
Cite as
Kazuhiro Inaba and Sebastian Maneth. The Complexity of Tree Transducer Output Languages. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 244-255, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{inaba_et_al:LIPIcs.FSTTCS.2008.1757,
author = {Inaba, Kazuhiro and Maneth, Sebastian},
title = {{The Complexity of Tree Transducer Output Languages}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {244--255},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1757},
URN = {urn:nbn:de:0030-drops-17570},
doi = {10.4230/LIPIcs.FSTTCS.2008.1757},
annote = {Keywords: Complexity, Tree Transducer, OI-hierarchy, Context-Sensitive}
}
Document
The unfolding of general Petri nets
Abstract
The unfolding of (1-)safe Petri nets to occurrence nets is well
understood. There is a universal characterization of the unfolding
of a safe net which is part and parcel of a coreflection from the
category of occurrence nets to the category of safe nets. The
unfolding of general Petri nets, nets with multiplicities on arcs
whose markings are multisets of places, does not possess a directly
analogous universal characterization, essentially because there is
an implicit symmetry in the multiplicities of general nets, and that
symmetry is not expressed in their traditional occurrence net
unfoldings. In the present paper, we show how to recover a
universal characterization by representing the symmetry in the
behaviour of the occurrence net unfoldings of general Petri nets. We
show that this is part of a coreflection between enriched categories
of general Petri nets with symmetry and occurrence nets with
symmetry.
Cite as
Jonathan Hayman and Glynn Winskel. The unfolding of general Petri nets. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 223-234, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)
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@InProceedings{hayman_et_al:LIPIcs.FSTTCS.2008.1755,
author = {Hayman, Jonathan and Winskel, Glynn},
title = {{The unfolding of general Petri nets}},
booktitle = {IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
pages = {223--234},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-08-8},
ISSN = {1868-8969},
year = {2008},
volume = {2},
editor = {Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1755},
URN = {urn:nbn:de:0030-drops-17552},
doi = {10.4230/LIPIcs.FSTTCS.2008.1755},
annote = {Keywords: Petri nets, symmetry, unfolding}
}