3 Search Results for "Oliva, Sergi"


Document
Track A: Algorithms, Complexity and Games
Multiparty Communication Complexity of Collision-Finding and Cutting Planes Proofs of Concise Pigeonhole Principles

Authors: Paul Beame and Michael Whitmeyer

Published in: LIPIcs, Volume 334, 52nd International Colloquium on Automata, Languages, and Programming (ICALP 2025)


Abstract
We prove several results concerning the communication complexity of a collision-finding problem, each of which has applications to the complexity of cutting-plane proofs, which make inferences based on integer linear inequalities. In particular, we prove an Ω(n^{1-1/k} log k /2^k) lower bound on the k-party number-in-hand communication complexity of collision-finding. This implies a 2^{n^{1-o(1)}} lower bound on the size of tree-like cutting-planes refutations of the bit pigeonhole principle CNFs, which are compact and natural propositional encodings of the negation of the pigeonhole principle, improving on the best previous lower bound of 2^{Ω(√n)}. Using the method of density-restoring partitions, we also extend that previous lower bound to the full range of pigeonhole parameters. Finally, using a refinement of a bottleneck-counting framework of Haken and Cook and Sokolov for DAG-like communication protocols, we give a 2^{Ω(n^{1/4})} lower bound on the size of fully general (not necessarily tree-like) cutting planes refutations of the same bit pigeonhole principle formulas, improving on the best previous lower bound of 2^{Ω(n^{1/8})}.

Cite as

Paul Beame and Michael Whitmeyer. Multiparty Communication Complexity of Collision-Finding and Cutting Planes Proofs of Concise Pigeonhole Principles. In 52nd International Colloquium on Automata, Languages, and Programming (ICALP 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 334, pp. 21:1-21:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{beame_et_al:LIPIcs.ICALP.2025.21,
  author =	{Beame, Paul and Whitmeyer, Michael},
  title =	{{Multiparty Communication Complexity of Collision-Finding and Cutting Planes Proofs of Concise Pigeonhole Principles}},
  booktitle =	{52nd International Colloquium on Automata, Languages, and Programming (ICALP 2025)},
  pages =	{21:1--21:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-372-0},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{334},
  editor =	{Censor-Hillel, Keren and Grandoni, Fabrizio and Ouaknine, Jo\"{e}l and Puppis, Gabriele},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2025.21},
  URN =		{urn:nbn:de:0030-drops-233982},
  doi =		{10.4230/LIPIcs.ICALP.2025.21},
  annote =	{Keywords: Proof Complexity, Communication Complexity}
}
Document
Structure-Guided Automated Reasoning

Authors: Max Bannach and Markus Hecher

Published in: LIPIcs, Volume 327, 42nd International Symposium on Theoretical Aspects of Computer Science (STACS 2025)


Abstract
Algorithmic meta-theorems state that problems definable in a fixed logic can be solved efficiently on structures with certain properties. An example is Courcelle’s Theorem, which states that all problems expressible in monadic second-order logic can be solved efficiently on structures of small treewidth. Such theorems are usually proven by algorithms for the model-checking problem of the logic, which is often complex and rarely leads to highly efficient solutions. Alternatively, we can solve the model-checking problem by grounding the given logic to propositional logic, for which dedicated solvers are available. Such encodings will, however, usually not preserve the input’s treewidth. This paper investigates whether all problems definable in monadic second-order logic can efficiently be encoded into SAT such that the input’s treewidth bounds the treewidth of the resulting formula. We answer this in the affirmative and, hence, provide an alternative proof of Courcelle’s Theorem. Our technique can naturally be extended: There are treewidth-aware reductions from the optimization version of Courcelle’s Theorem to MAXSAT and from the counting version of the theorem to #SAT. By using encodings to SAT, we obtain, ignoring polynomial factors, the same running time for the model-checking problem as we would with dedicated algorithms. Another immediate consequence is a treewidth-preserving reduction from the model-checking problem of monadic second-order logic to integer linear programming (ILP). We complement our upper bounds with new lower bounds based on ETH; and we show that the block size of the input’s formula and the treewidth of the input’s structure are tightly linked. Finally, we present various side results needed to prove the main theorems: A treewidth-preserving cardinality constraints, treewidth-preserving encodings from CNFs into DNFs, and a treewidth-aware quantifier elimination scheme for QBF implying a treewidth-preserving reduction from QSAT to SAT. We also present a reduction from projected model counting to #SAT that increases the treewidth by at most a factor of 2^{k+3.59}, yielding a algorithm for projected model counting that beats the currently best running time of 2^{2^{k+4}}⋅poly(|ψ|).

Cite as

Max Bannach and Markus Hecher. Structure-Guided Automated Reasoning. In 42nd International Symposium on Theoretical Aspects of Computer Science (STACS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 327, pp. 15:1-15:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{bannach_et_al:LIPIcs.STACS.2025.15,
  author =	{Bannach, Max and Hecher, Markus},
  title =	{{Structure-Guided Automated Reasoning}},
  booktitle =	{42nd International Symposium on Theoretical Aspects of Computer Science (STACS 2025)},
  pages =	{15:1--15:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-365-2},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{327},
  editor =	{Beyersdorff, Olaf and Pilipczuk, Micha{\l} and Pimentel, Elaine and Thắng, Nguy\~{ê}n Kim},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2025.15},
  URN =		{urn:nbn:de:0030-drops-228408},
  doi =		{10.4230/LIPIcs.STACS.2025.15},
  annote =	{Keywords: automated reasoning, treewidth, satisfiability, max-sat, sharp-sat, monadic second-order logic, fixed-parameter tractability}
}
Document
Bounded-width QBF is PSPACE-complete

Authors: Albert Atserias and Sergi Oliva

Published in: LIPIcs, Volume 20, 30th International Symposium on Theoretical Aspects of Computer Science (STACS 2013)


Abstract
Tree-width is a well-studied parameter of structures that measures their similarity to a tree. Many important NP-complete problems, such as Boolean satisfiability (SAT), are tractable on bounded tree-width instances. In this paper we focus on the canonical PSPACE-complete problem QBF, the fully-quantified version of SAT. It was shown by Pan and Vardi [LICS 2006] that this problem is PSPACE-complete even for formulas whose tree-width grows extremely slowly. Vardi also posed the question of whether the problem is tractable when restricted to instances of bounded tree-width. We answer this question by showing that QBF on instances with constant tree-width is PSPACE-complete.

Cite as

Albert Atserias and Sergi Oliva. Bounded-width QBF is PSPACE-complete. In 30th International Symposium on Theoretical Aspects of Computer Science (STACS 2013). Leibniz International Proceedings in Informatics (LIPIcs), Volume 20, pp. 44-54, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2013)


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@InProceedings{atserias_et_al:LIPIcs.STACS.2013.44,
  author =	{Atserias, Albert and Oliva, Sergi},
  title =	{{Bounded-width QBF is PSPACE-complete}},
  booktitle =	{30th International Symposium on Theoretical Aspects of Computer Science (STACS 2013)},
  pages =	{44--54},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-50-7},
  ISSN =	{1868-8969},
  year =	{2013},
  volume =	{20},
  editor =	{Portier, Natacha and Wilke, Thomas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2013.44},
  URN =		{urn:nbn:de:0030-drops-39217},
  doi =		{10.4230/LIPIcs.STACS.2013.44},
  annote =	{Keywords: Tree-width, QBF, PSPACE-complete}
}
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