4 Search Results for "Alur, Rajeev"

Document
DOI: 10.4230/DagRep.13.5.96
Regular Transformations (Dagstuhl Seminar 23202)

Authors: Rajeev Alur, Mikołaj Bojańczyk, Emmanuel Filiot, Anca Muscholl, and Sarah Winter

Published in: Dagstuhl Reports, Volume 13, Issue 5 (2023)

Abstract
This report documents the program and the outcomes of the Dagstuhl Seminar 23202 "Regular Transformations". The goal of this seminar was to advance on a list of topics about transducers that have gathered much interest recently, and to explore new connections between the theory of regular transformations and its applications in linguistics.
Cite as

Rajeev Alur, Mikołaj Bojańczyk, Emmanuel Filiot, Anca Muscholl, and Sarah Winter. Regular Transformations (Dagstuhl Seminar 23202). In Dagstuhl Reports, Volume 13, Issue 5, pp. 96-113, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@Article{alur_et_al:DagRep.13.5.96,
  author =	{Alur, Rajeev and Boja\'{n}czyk, Miko{\l}aj and Filiot, Emmanuel and Muscholl, Anca and Winter, Sarah},
  title =	{{Regular Transformations (Dagstuhl Seminar 23202)}},
  pages =	{96--113},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2023},
  volume =	{13},
  number =	{5},
  editor =	{Alur, Rajeev and Boja\'{n}czyk, Miko{\l}aj and Filiot, Emmanuel and Muscholl, Anca and Winter, Sarah},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.13.5.96},
  URN =		{urn:nbn:de:0030-drops-193663},
  doi =		{10.4230/DagRep.13.5.96},
  annote =	{Keywords: transducers; (poly-)regular functions; linguistic transformations}
}
Document
DOI: 10.4230/LIPIcs.ICALP.2017.112
Automata-Based Stream Processing

Authors: Rajeev Alur, Konstantinos Mamouras, and Caleb Stanford

Published in: LIPIcs, Volume 80, 44th International Colloquium on Automata, Languages, and Programming (ICALP 2017)

Abstract
We propose an automata-theoretic framework for modularly expressing computations on streams of data. With weighted automata as a starting point, we identify three key features that are useful for an automaton model for stream processing: expressing the regular decomposition of streams whose data items are elements of a complex type (e.g., tuple of values), allowing the hierarchical nesting of several different kinds of aggregations, and specifying modularly the parallel execution and combination of various subcomputations. The combination of these features leads to subtle efficiency considerations that concern the interaction between nondeterminism, hierarchical nesting, and parallelism. We identify a syntactic restriction where the nondeterminism is unambiguous and parallel subcomputations synchronize their outputs. For automata satisfying these restrictions, we show that there is a space- and time-efficient streaming evaluation algorithm. We also prove that when these restrictions are relaxed, the evaluation problem becomes inherently computationally expensive.
Cite as

Rajeev Alur, Konstantinos Mamouras, and Caleb Stanford. Automata-Based Stream Processing. In 44th International Colloquium on Automata, Languages, and Programming (ICALP 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 80, pp. 112:1-112:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{alur_et_al:LIPIcs.ICALP.2017.112,
  author =	{Alur, Rajeev and Mamouras, Konstantinos and Stanford, Caleb},
  title =	{{Automata-Based Stream Processing}},
  booktitle =	{44th International Colloquium on Automata, Languages, and Programming (ICALP 2017)},
  pages =	{112:1--112:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-041-5},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{80},
  editor =	{Chatzigiannakis, Ioannis and Indyk, Piotr and Kuhn, Fabian and Muscholl, Anca},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2017.112},
  URN =		{urn:nbn:de:0030-drops-74720},
  doi =		{10.4230/LIPIcs.ICALP.2017.112},
  annote =	{Keywords: weighted automata, Quantitative Regular Expressions, stream processing}
}
Document
DOI: 10.4230/LIPIcs.CSL.2016.29
Hedging Bets in Markov Decision Processes

Authors: Rajeev Alur, Marco Faella, Sampath Kannan, and Nimit Singhania

Published in: LIPIcs, Volume 62, 25th EACSL Annual Conference on Computer Science Logic (CSL 2016)

Abstract
The classical model of Markov decision processes with costs or rewards, while widely used to formalize optimal decision making, cannot capture scenarios where there are multiple objectives for the agent during the system evolution, but only one of these objectives gets actualized upon termination. We introduce the model of Markov decision processes with alternative objectives (MDPAO) for formalizing optimization in such scenarios. To compute the strategy to optimize the expected cost/reward upon termination, we need to figure out how to balance the values of the alternative objectives. This requires analysis of the underlying infinite-state process that tracks the accumulated values of all the objectives. While the decidability of the problem of computing the exact optimal strategy for the general model remains open, we present the following results. First, for a Markov chain with alternative objectives, the optimal expected cost/reward can be computed in polynomial-time. Second, for a single-state process with two actions and multiple objectives we show how to compute the optimal decision strategy. Third, for a process with only two alternative objectives, we present a reduction to the minimum expected accumulated reward problem for one-counter MDPs, and this leads to decidability for this case under some technical restrictions. Finally, we show that optimal cost/reward can be approximated up to a constant additive factor for the general problem.
Cite as

Rajeev Alur, Marco Faella, Sampath Kannan, and Nimit Singhania. Hedging Bets in Markov Decision Processes. In 25th EACSL Annual Conference on Computer Science Logic (CSL 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 62, pp. 29:1-29:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

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@InProceedings{alur_et_al:LIPIcs.CSL.2016.29,
  author =	{Alur, Rajeev and Faella, Marco and Kannan, Sampath and Singhania, Nimit},
  title =	{{Hedging Bets in Markov Decision Processes}},
  booktitle =	{25th EACSL Annual Conference on Computer Science Logic (CSL 2016)},
  pages =	{29:1--29:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-022-4},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{62},
  editor =	{Talbot, Jean-Marc and Regnier, Laurent},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2016.29},
  URN =		{urn:nbn:de:0030-drops-65698},
  doi =		{10.4230/LIPIcs.CSL.2016.29},
  annote =	{Keywords: Markov decision processes, Infinite state systems, Multi-objective optimization}
}
Document
DOI: 10.4230/LIPIcs.FSTTCS.2010.1
Expressiveness of streaming string transducers

Authors: Rajeev Alur and Pavol Černý

Published in: LIPIcs, Volume 8, IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2010)

Abstract
Streaming string transducers define (partial) functions from input strings to output strings. A streaming string transducer makes a single pass through the input string and uses a finite set of variables that range over strings from the output alphabet. At every step, the transducer processes an input symbol, and updates all the variables in parallel using assignments whose right-hand-sides are concatenations of output symbols and variables with the restriction that a variable can be used at most once in a right-hand-side expression. It has been shown that streaming string transducers operating on strings over infinite data domains are of interest in algorithmic verification of list-processing programs, as they lead to Pspace decision procedures for checking pre/postconditions and for checking semantic equivalence, for a well-defined class of heap-manipulating programs. In order to understand the theoretical expressiveness of streaming transducers, we focus on streaming transducers processing strings over finite alphabets, given the existence of a robust and well-studied class of ``regular'' transductions for this case. Such regular transductions can be defined either by two-way deterministic finite-state transducers, or using a logical MSO-based characterization. Our main result is that the expressiveness of streaming string transducers coincides exactly with this class of regular transductions.
Cite as

Rajeev Alur and Pavol Černý. Expressiveness of streaming string transducers. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2010). Leibniz International Proceedings in Informatics (LIPIcs), Volume 8, pp. 1-12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{alur_et_al:LIPIcs.FSTTCS.2010.1,
  author =	{Alur, Rajeev and \v{C}ern\'{y}, Pavol},
  title =	{{Expressiveness of streaming string transducers}},
  booktitle =	{IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2010)},
  pages =	{1--12},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-23-1},
  ISSN =	{1868-8969},
  year =	{2010},
  volume =	{8},
  editor =	{Lodaya, Kamal and Mahajan, Meena},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2010.1},
  URN =		{urn:nbn:de:0030-drops-28538},
  doi =		{10.4230/LIPIcs.FSTTCS.2010.1},
  annote =	{Keywords: streaming string transducer, list processing, heap manipulation, monadic second-order transduction}
}
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