10 Search Results for "D�hrkop, Kai"


Document
Online Mergers and Applications to Registration-Based Encryption and Accumulators

Authors: Mohammad Mahmoody and Wei Qi

Published in: LIPIcs, Volume 267, 4th Conference on Information-Theoretic Cryptography (ITC 2023)


Abstract
In this work we study a new information theoretic problem, called online merging, that has direct applications for constructing public-state accumulators and registration-based encryption schemes. An {online merger} receives the sequence of sets {1}, {2}, … in an online way, and right after receiving {i}, it can re-partition the elements 1,…,i into T₁,…,T_{m_i} by merging some of these sets. The goal of the merger is to balance the trade-off between the maximum number of sets wid = max_{i ∈ [n]} m_i that co-exist at any moment, called the width of the scheme, with its depth dep = max_{i ∈ [n]} d_i, where d_i is the number of times that the sets that contain i get merged. An online merger can be used to maintain a set of Merkle trees that occasionally get merged. An online merger can be directly used to obtain public-state accumulators (using collision-resistant hashing) and registration-based encryptions (relying on more assumptions). Doing so, the width of an online merger translates into the size of the public-parameter of the constructed scheme, and the depth of the online algorithm corresponds to the number of times that parties need to update their "witness" (for accumulators) or their decryption key (for RBE). In this work, we construct online mergers with poly(log n) width and O(log n / log log n) depth, which can be shown to be optimal for all schemes with poly(log n) width. More generally, we show how to achieve optimal depth for a given fixed width and to achieve a 2-approximate optimal width for a given depth d that can possibly grow as a function of n (e.g., d = 2 or d = log n / log log n). As applications, we obtain accumulators with O(log n / log log n) number of updates for parties' witnesses (which can be shown to be optimal for accumulator digests of length poly(log n)) as well as registration based encryptions that again have an optimal O(log n / log log n) number of decryption updates, resolving the open question of Mahmoody, Rahimi, Qi [TCC'22] who proved that Ω(log n / log log n) number of decryption updates are necessary for any RBE (with public parameter of length poly(log n)). More generally, for any given number of decryption updates d = d(n) (under believable computational assumptions) our online merger implies RBE schemes with public parameters of length that is optimal, up to a constant factor that depends on the security parameter. For example, for any constant number of updates d, we get RBE schemes with public parameters of length O(n^{1/(d+1)}).

Cite as

Mohammad Mahmoody and Wei Qi. Online Mergers and Applications to Registration-Based Encryption and Accumulators. In 4th Conference on Information-Theoretic Cryptography (ITC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 267, pp. 15:1-15:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{mahmoody_et_al:LIPIcs.ITC.2023.15,
  author =	{Mahmoody, Mohammad and Qi, Wei},
  title =	{{Online Mergers and Applications to Registration-Based Encryption and Accumulators}},
  booktitle =	{4th Conference on Information-Theoretic Cryptography (ITC 2023)},
  pages =	{15:1--15:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-271-6},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{267},
  editor =	{Chung, Kai-Min},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ITC.2023.15},
  URN =		{urn:nbn:de:0030-drops-183432},
  doi =		{10.4230/LIPIcs.ITC.2023.15},
  annote =	{Keywords: Registration-based encryption, Accumulators, Merkle Trees}
}
Document
Improving Local Search for Minimum Weighted Connected Dominating Set Problem by Inner-Layer Local Search

Authors: Bohan Li, Kai Wang, Yiyuan Wang, and Shaowei Cai

Published in: LIPIcs, Volume 210, 27th International Conference on Principles and Practice of Constraint Programming (CP 2021)


Abstract
The minimum weighted connected dominating set (MWCDS) problem is an important variant of connected dominating set problems with wide applications, especially in heterogenous networks and gene regulatory networks. In the paper, we develop a nested local search algorithm called NestedLS for solving MWCDS on classic benchmarks and massive graphs. In this local search framework, we propose two novel ideas to make it effective by utilizing previous search information. First, we design the restart based smoothing mechanism as a diversification method to escape from local optimal. Second, we propose a novel inner-layer local search method to enlarge the candidate removal set, which can be modelled as an optimized version of spanning tree problem. Moreover, inner-layer local search method is a general method for maintaining the connectivity constraint when dealing with massive graphs. Experimental results show that NestedLS outperforms state-of-the-art meta-heuristic algorithms on most instances.

Cite as

Bohan Li, Kai Wang, Yiyuan Wang, and Shaowei Cai. Improving Local Search for Minimum Weighted Connected Dominating Set Problem by Inner-Layer Local Search. In 27th International Conference on Principles and Practice of Constraint Programming (CP 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 210, pp. 39:1-39:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{li_et_al:LIPIcs.CP.2021.39,
  author =	{Li, Bohan and Wang, Kai and Wang, Yiyuan and Cai, Shaowei},
  title =	{{Improving Local Search for Minimum Weighted Connected Dominating Set Problem by Inner-Layer Local Search}},
  booktitle =	{27th International Conference on Principles and Practice of Constraint Programming (CP 2021)},
  pages =	{39:1--39:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-211-2},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{210},
  editor =	{Michel, Laurent D.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2021.39},
  URN =		{urn:nbn:de:0030-drops-153304},
  doi =		{10.4230/LIPIcs.CP.2021.39},
  annote =	{Keywords: Operations Research, NP-hard Problem, Local Search, Weighted Connected Dominating Set Problem}
}
Document
Lower Bounds for Function Inversion with Quantum Advice

Authors: Kai-Min Chung, Tai-Ning Liao, and Luowen Qian

Published in: LIPIcs, Volume 163, 1st Conference on Information-Theoretic Cryptography (ITC 2020)


Abstract
Function inversion is the problem that given a random function f: [M] → [N], we want to find pre-image of any image f^{-1}(y) in time T. In this work, we revisit this problem under the preprocessing model where we can compute some auxiliary information or advice of size S that only depends on f but not on y. It is a well-studied problem in the classical settings, however, it is not clear how quantum algorithms can solve this task any better besides invoking Grover’s algorithm [Grover, 1996], which does not leverage the power of preprocessing. Nayebi et al. [Nayebi et al., 2015] proved a lower bound ST² ≥ ̃Ω(N) for quantum algorithms inverting permutations, however, they only consider algorithms with classical advice. Hhan et al. [Minki Hhan et al., 2019] subsequently extended this lower bound to fully quantum algorithms for inverting permutations. In this work, we give the same asymptotic lower bound to fully quantum algorithms for inverting functions for fully quantum algorithms under the regime where M = O(N). In order to prove these bounds, we generalize the notion of quantum random access code, originally introduced by Ambainis et al. [Ambainis et al., 1999], to the setting where we are given a list of (not necessarily independent) random variables, and we wish to compress them into a variable-length encoding such that we can retrieve a random element just using the encoding with high probability. As our main technical contribution, we give a nearly tight lower bound (for a wide parameter range) for this generalized notion of quantum random access codes, which may be of independent interest.

Cite as

Kai-Min Chung, Tai-Ning Liao, and Luowen Qian. Lower Bounds for Function Inversion with Quantum Advice. In 1st Conference on Information-Theoretic Cryptography (ITC 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 163, pp. 8:1-8:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{chung_et_al:LIPIcs.ITC.2020.8,
  author =	{Chung, Kai-Min and Liao, Tai-Ning and Qian, Luowen},
  title =	{{Lower Bounds for Function Inversion with Quantum Advice}},
  booktitle =	{1st Conference on Information-Theoretic Cryptography (ITC 2020)},
  pages =	{8:1--8:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-151-1},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{163},
  editor =	{Tauman Kalai, Yael and Smith, Adam D. and Wichs, Daniel},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ITC.2020.8},
  URN =		{urn:nbn:de:0030-drops-121134},
  doi =		{10.4230/LIPIcs.ITC.2020.8},
  annote =	{Keywords: Cryptanalysis, Data Structures, Quantum Query Complexity}
}
Document
Oblivious Parallel Tight Compaction

Authors: Gilad Asharov, Ilan Komargodski, Wei-Kai Lin, Enoch Peserico, and Elaine Shi

Published in: LIPIcs, Volume 163, 1st Conference on Information-Theoretic Cryptography (ITC 2020)


Abstract
In tight compaction one is given an array of balls some of which are marked 0 and the rest are marked 1. The output of the procedure is an array that contains all of the original balls except that now the 0-balls appear before the 1-balls. In other words, tight compaction is equivalent to sorting the array according to 1-bit keys (not necessarily maintaining order within same-key balls). Tight compaction is not only an important algorithmic task by itself, but its oblivious version has also played a key role in recent constructions of oblivious RAM compilers. We present an oblivious deterministic algorithm for tight compaction such that for input arrays of n balls requires O(n) total work and O(log n) depth. Our algorithm is in the Exclusive-Read-Exclusive-Write Parallel-RAM model (i.e., EREW PRAM, the most restrictive PRAM model), and importantly we achieve asymptotical optimality in both total work and depth. To the best of our knowledge no earlier work, even when allowing randomization, can achieve optimality in both total work and depth.

Cite as

Gilad Asharov, Ilan Komargodski, Wei-Kai Lin, Enoch Peserico, and Elaine Shi. Oblivious Parallel Tight Compaction. In 1st Conference on Information-Theoretic Cryptography (ITC 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 163, pp. 11:1-11:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{asharov_et_al:LIPIcs.ITC.2020.11,
  author =	{Asharov, Gilad and Komargodski, Ilan and Lin, Wei-Kai and Peserico, Enoch and Shi, Elaine},
  title =	{{Oblivious Parallel Tight Compaction}},
  booktitle =	{1st Conference on Information-Theoretic Cryptography (ITC 2020)},
  pages =	{11:1--11:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-151-1},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{163},
  editor =	{Tauman Kalai, Yael and Smith, Adam D. and Wichs, Daniel},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ITC.2020.11},
  URN =		{urn:nbn:de:0030-drops-121164},
  doi =		{10.4230/LIPIcs.ITC.2020.11},
  annote =	{Keywords: Oblivious tight compaction, parallel oblivious RAM, EREW PRAM}
}
Document
An O(1)-Approximation Algorithm for Dynamic Weighted Vertex Cover with Soft Capacity

Authors: Hao-Ting Wei, Wing-Kai Hon, Paul Horn, Chung-Shou Liao, and Kunihiko Sadakane

Published in: LIPIcs, Volume 116, Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2018)


Abstract
This study considers the soft capacitated vertex cover problem in a dynamic setting. This problem generalizes the dynamic model of the vertex cover problem, which has been intensively studied in recent years. Given a dynamically changing vertex-weighted graph G=(V,E), which allows edge insertions and edge deletions, the goal is to design a data structure that maintains an approximate minimum vertex cover while satisfying the capacity constraint of each vertex. That is, when picking a copy of a vertex v in the cover, the number of v's incident edges covered by the copy is up to a given capacity of v. We extend Bhattacharya et al.'s work [SODA'15 and ICALP'15] to obtain a deterministic primal-dual algorithm for maintaining a constant-factor approximate minimum capacitated vertex cover with O(log n / epsilon) amortized update time, where n is the number of vertices in the graph. The algorithm can be extended to (1) a more general model in which each edge is associated with a non-uniform and unsplittable demand, and (2) the more general capacitated set cover problem.

Cite as

Hao-Ting Wei, Wing-Kai Hon, Paul Horn, Chung-Shou Liao, and Kunihiko Sadakane. An O(1)-Approximation Algorithm for Dynamic Weighted Vertex Cover with Soft Capacity. In Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 116, pp. 27:1-27:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


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@InProceedings{wei_et_al:LIPIcs.APPROX-RANDOM.2018.27,
  author =	{Wei, Hao-Ting and Hon, Wing-Kai and Horn, Paul and Liao, Chung-Shou and Sadakane, Kunihiko},
  title =	{{An O(1)-Approximation Algorithm for Dynamic Weighted Vertex Cover with Soft Capacity}},
  booktitle =	{Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2018)},
  pages =	{27:1--27:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-085-9},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{116},
  editor =	{Blais, Eric and Jansen, Klaus and D. P. Rolim, Jos\'{e} and Steurer, David},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.APPROX-RANDOM.2018.27},
  URN =		{urn:nbn:de:0030-drops-94312},
  doi =		{10.4230/LIPIcs.APPROX-RANDOM.2018.27},
  annote =	{Keywords: approximation algorithm, dynamic algorithm, primal-dual, vertex cover}
}
Document
Heuristic Algorithms for the Maximum Colorful Subtree Problem

Authors: Kai Dührkop, Marie A. Lataretu, W. Timothy J. White, and Sebastian Böcker

Published in: LIPIcs, Volume 113, 18th International Workshop on Algorithms in Bioinformatics (WABI 2018)


Abstract
In metabolomics, small molecules are structurally elucidated using tandem mass spectrometry (MS/MS); this computational task can be formulated as the Maximum Colorful Subtree problem, which is NP-hard. Unfortunately, data from a single metabolite requires us to solve hundreds or thousands of instances of this problem - and in a single Liquid Chromatography MS/MS run, hundreds or thousands of metabolites are measured. Here, we comprehensively evaluate the performance of several heuristic algorithms for the problem. Unfortunately, as is often the case in bioinformatics, the structure of the (chemically) true solution is not known to us; therefore we can only evaluate against the optimal solution of an instance. Evaluating the quality of a heuristic based on scores can be misleading: Even a slightly suboptimal solution can be structurally very different from the optimal solution, but it is the structure of a solution and not its score that is relevant for the downstream analysis. To this end, we propose a different evaluation setup: Given a set of candidate instances of which exactly one is known to be correct, the heuristic in question solves each instance to the best of its ability, producing a score for each instance, which is then used to rank the instances. We then evaluate whether the correct instance is ranked highly by the heuristic. We find that one particular heuristic consistently ranks the correct instance in a top position. We also find that the scores of the best heuristic solutions are very close to the optimal score; in contrast, the structure of the solutions can deviate significantly from the optimal structures. Integrating the heuristic allowed us to speed up computations in practice by a factor of 100-fold.

Cite as

Kai Dührkop, Marie A. Lataretu, W. Timothy J. White, and Sebastian Böcker. Heuristic Algorithms for the Maximum Colorful Subtree Problem. In 18th International Workshop on Algorithms in Bioinformatics (WABI 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 113, pp. 23:1-23:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


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@InProceedings{duhrkop_et_al:LIPIcs.WABI.2018.23,
  author =	{D\"{u}hrkop, Kai and Lataretu, Marie A. and White, W. Timothy J. and B\"{o}cker, Sebastian},
  title =	{{Heuristic Algorithms for the Maximum Colorful Subtree Problem}},
  booktitle =	{18th International Workshop on Algorithms in Bioinformatics (WABI 2018)},
  pages =	{23:1--23:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-082-8},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{113},
  editor =	{Parida, Laxmi and Ukkonen, Esko},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.WABI.2018.23},
  URN =		{urn:nbn:de:0030-drops-93256},
  doi =		{10.4230/LIPIcs.WABI.2018.23},
  annote =	{Keywords: Fragmentation trees, Computational mass spectrometry}
}
Document
Beyond VR and AR: Reimagining Experience Sharing and Skill Transfer Towards an Internet of Abilities (Dagstuhl Seminar 17062)

Authors: Anind D. Dey, Jonna Häkkilä, Niels Henze, and Kai Kunze

Published in: Dagstuhl Reports, Volume 7, Issue 2 (2017)


Abstract
With recent development in capture technology, preserving one's daily experiences and one's knowledge becomes richer and more comprehensive. Furthermore, new recording technologies beyond simple audio/video recordings become available: 360° videos, tactile recorders and even odor recorders are becoming available. The new recording technology and the massive amounts of data require new means for selecting, displaying and sharing experiences. This seminar brought together researchers from a wide range of computing disciplines, including virtual reality, mobile computing, privacy and security, social computing and ethnography, usability, and systems research. Through lightning talk, thematic sessions and hands-on workshops, the seminar investigated the future of interaction beyond virtual and augmented reality. Participants reimagined experience sharing and skill transfer towards an Internet of abilities. We conclude with a set of open and guiding questions for the future of our field.

Cite as

Anind D. Dey, Jonna Häkkilä, Niels Henze, and Kai Kunze. Beyond VR and AR: Reimagining Experience Sharing and Skill Transfer Towards an Internet of Abilities (Dagstuhl Seminar 17062). In Dagstuhl Reports, Volume 7, Issue 2, pp. 23-47, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)


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@Article{dey_et_al:DagRep.7.2.23,
  author =	{Dey, Anind D. and H\"{a}kkil\"{a}, Jonna and Henze, Niels and Kunze, Kai},
  title =	{{Beyond VR and AR: Reimagining Experience Sharing and Skill Transfer Towards an Internet of Abilities (Dagstuhl Seminar 17062)}},
  pages =	{23--47},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2017},
  volume =	{7},
  number =	{2},
  editor =	{Dey, Anind D. and H\"{a}kkil\"{a}, Jonna and Henze, Niels and Kunze, Kai},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.7.2.23},
  URN =		{urn:nbn:de:0030-drops-73519},
  doi =		{10.4230/DagRep.7.2.23},
  annote =	{Keywords: Augmented Reality, Virtual Reality, Skill Transfer}
}
Document
Space-Efficient Dictionaries for Parameterized and Order-Preserving Pattern Matching

Authors: Arnab Ganguly, Wing-Kai Hon, Kunihiko Sadakane, Rahul Shah, Sharma V. Thankachan, and Yilin Yang

Published in: LIPIcs, Volume 54, 27th Annual Symposium on Combinatorial Pattern Matching (CPM 2016)


Abstract
Let S and S' be two strings of the same length.We consider the following two variants of string matching. * Parameterized Matching: The characters of S and S' are partitioned into static characters and parameterized characters. The strings are parameterized match iff the static characters match exactly and there exists a one-to-one function which renames the parameterized characters in S to those in S'. * Order-Preserving Matching: The strings are order-preserving match iff for any two integers i,j in [1,|S|], S[i] <= S[j] iff S'[i] <= S'[j]. Let P be a collection of d patterns {P_1, P_2, ..., P_d} of total length n characters, which are chosen from an alphabet Sigma. Given a text T, also over Sigma, we consider the dictionary indexing problem under the above definitions of string matching. Specifically, the task is to index P, such that we can report all positions j where at least one of the patterns P_i in P is a parameterized-match (resp. order-preserving match) with the same-length substring of $T$ starting at j. Previous best-known indexes occupy O(n * log(n)) bits and can report all occ positions in O(|T| * log(|Sigma|) + occ) time. We present space-efficient indexes that occupy O(n * log(|Sigma|+d) * log(n)) bits and reports all occ positions in O(|T| * (log(|Sigma|) + log_{|Sigma|}(n)) + occ) time for parameterized matching and in O(|T| * log(n) + occ) time for order-preserving matching.

Cite as

Arnab Ganguly, Wing-Kai Hon, Kunihiko Sadakane, Rahul Shah, Sharma V. Thankachan, and Yilin Yang. Space-Efficient Dictionaries for Parameterized and Order-Preserving Pattern Matching. In 27th Annual Symposium on Combinatorial Pattern Matching (CPM 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 54, pp. 2:1-2:12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)


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@InProceedings{ganguly_et_al:LIPIcs.CPM.2016.2,
  author =	{Ganguly, Arnab and Hon, Wing-Kai and Sadakane, Kunihiko and Shah, Rahul and Thankachan, Sharma V. and Yang, Yilin},
  title =	{{Space-Efficient Dictionaries for Parameterized and Order-Preserving Pattern Matching}},
  booktitle =	{27th Annual Symposium on Combinatorial Pattern Matching (CPM 2016)},
  pages =	{2:1--2:12},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-012-5},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{54},
  editor =	{Grossi, Roberto and Lewenstein, Moshe},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CPM.2016.2},
  URN =		{urn:nbn:de:0030-drops-60736},
  doi =		{10.4230/LIPIcs.CPM.2016.2},
  annote =	{Keywords: Parameterized Matching, Order-preserving Matching, Dictionary Indexing, Aho-Corasick Automaton, Sparsification}
}
Document
A Framework for Dynamic Parameterized Dictionary Matching

Authors: Arnab Ganguly, Wing-Kai Hon, and Rahul Shah

Published in: LIPIcs, Volume 53, 15th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT 2016)


Abstract
Two equal-length strings S and S' are a parameterized-match (p-match) iff there exists a one-to-one function that renames the characters in S to those in S'. Let P be a collection of d patterns of total length n characters that are chosen from an alphabet Sigma of cardinality sigma. The task is to index P such that we can support the following operations. * search(T): given a text T, report all occurrences <j,P_i> such that there exists a pattern P_i in P that is a p-match with the substring T[j,j+|P_i|-1]. * ins(P_i)/del(P_i): modify the index when a pattern P_i is inserted/deleted. We present a linear-space index that occupies O(n*log n) bits and supports (i) search(T) in worst-case O(|T|*log^2 n + occ) time, where occ is the number of occurrences reported, and (ii) ins(P_i) and del(P_i) in amortized O(|P_i|*polylog(n)) time. Then, we present a succinct index that occupies (1+o(1))n*log sigma + O(d*log n) bits and supports (i) search(T) in worst-case O(|T|*log^2 n + occ) time, and (ii) ins(P_i) and del(P_i) in amortized O(|P_i|*polylog(n)) time. We also present results related to the semi-dynamic variant of the problem, where deletion is not allowed.

Cite as

Arnab Ganguly, Wing-Kai Hon, and Rahul Shah. A Framework for Dynamic Parameterized Dictionary Matching. In 15th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 53, pp. 10:1-10:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)


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@InProceedings{ganguly_et_al:LIPIcs.SWAT.2016.10,
  author =	{Ganguly, Arnab and Hon, Wing-Kai and Shah, Rahul},
  title =	{{A Framework for Dynamic Parameterized Dictionary Matching}},
  booktitle =	{15th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT 2016)},
  pages =	{10:1--10:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-011-8},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{53},
  editor =	{Pagh, Rasmus},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.SWAT.2016.10},
  URN =		{urn:nbn:de:0030-drops-60256},
  doi =		{10.4230/LIPIcs.SWAT.2016.10},
  annote =	{Keywords: Parameterized Dictionary Indexing, Generalized Suffix Tree, Succinct Data Structures, Sparsification}
}
Document
Chernoff-Hoeffding Bounds for Markov Chains: Generalized and Simplified

Authors: Kai-Min Chung, Henry Lam, Zhenming Liu, and Michael Mitzenmacher

Published in: LIPIcs, Volume 14, 29th International Symposium on Theoretical Aspects of Computer Science (STACS 2012)


Abstract
We prove the first Chernoff-Hoeffding bounds for general nonreversible finite-state Markov chains based on the standard L_1 (variation distance) mixing-time of the chain. Specifically, consider an ergodic Markov chain M and a weight function f: [n] -> [0,1] on the state space [n] of M with mean mu = E_{v <- pi}[f(v)], where pi is the stationary distribution of M. A t-step random walk (v_1,...,v_t) on M starting from the stationary distribution pi has expected total weight E[X] = mu t, where X = sum_{i=1}^t f(v_i). Let T be the L_1 mixing-time of M. We show that the probability of X deviating from its mean by a multiplicative factor of delta, i.e., Pr [ |X - mu t| >= delta mu t ], is at most exp(-Omega( delta^2 mu t / T )) for 0 <= delta <= 1, and exp(-Omega( delta mu t / T )) for delta > 1. In fact, the bounds hold even if the weight functions f_i's for i in [t] are distinct, provided that all of them have the same mean mu. We also obtain a simplified proof for the Chernoff-Hoeffding bounds based on the spectral expansion lambda of M, which is the square root of the second largest eigenvalue (in absolute value) of M tilde{M}, where tilde{M} is the time-reversal Markov chain of M. We show that the probability Pr [ |X - mu t| >= delta mu t ] is at most exp(-Omega( delta^2 (1-lambda) mu t )) for 0 <= delta <= 1, and exp(-Omega( delta (1-lambda) mu t )) for delta > 1. Both of our results extend to continuous-time Markov chains, and to the case where the walk starts from an arbitrary distribution x, at a price of a multiplicative factor depending on the distribution x in the concentration bounds.

Cite as

Kai-Min Chung, Henry Lam, Zhenming Liu, and Michael Mitzenmacher. Chernoff-Hoeffding Bounds for Markov Chains: Generalized and Simplified. In 29th International Symposium on Theoretical Aspects of Computer Science (STACS 2012). Leibniz International Proceedings in Informatics (LIPIcs), Volume 14, pp. 124-135, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2012)


Copy BibTex To Clipboard

@InProceedings{chung_et_al:LIPIcs.STACS.2012.124,
  author =	{Chung, Kai-Min and Lam, Henry and Liu, Zhenming and Mitzenmacher, Michael},
  title =	{{Chernoff-Hoeffding Bounds for Markov Chains: Generalized and Simplified}},
  booktitle =	{29th International Symposium on Theoretical Aspects of Computer Science (STACS 2012)},
  pages =	{124--135},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-35-4},
  ISSN =	{1868-8969},
  year =	{2012},
  volume =	{14},
  editor =	{D\"{u}rr, Christoph and Wilke, Thomas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2012.124},
  URN =		{urn:nbn:de:0030-drops-34374},
  doi =		{10.4230/LIPIcs.STACS.2012.124},
  annote =	{Keywords: probabilistic analysis, tail bounds, Markov chains}
}
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