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Electronic Colloquium on Computational Complexity

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All reports by Author Leroy Chew:

TR21-144 | 13th October 2021
Leroy Chew, Friedrich Slivovsky

Towards Uniform Certification in QBF

We pioneer a new technique that allows us to prove a multitude of previously open simulations in QBF proof complexity. In particular, we show that extended QBF Frege p-simulates clausal proof systems such as IR-Calculus, IRM-Calculus, Long-Distance Q-Resolution, and Merge Resolution.
These results are obtained by taking a technique ... more >>>

TR20-159 | 9th October 2020
Leroy Chew, Marijn Heule

Relating existing powerful proof systems for QBF

We advance the theory of QBF proof systems by showing the first simulation of the universal checking format QRAT by a theory-friendly system. We show that the sequent system G fully p-simulates QRAT, including the Extended Universal Reduction (EUR) rule which was recently used to show QRAT does not ... more >>>

TR19-157 | 25th September 2019
Leroy Chew, Judith Clymo

How QBF Expansion Makes Strategy Extraction Hard

In this paper we show that the QBF proof checking format QRAT (Quantified Resolution Asymmetric Tautologies) by Heule, Biere and Seidl cannot have polynomial-time strategy extraction unless P=PSPACE. In our proof, the crucial property that makes strategy extraction PSPACE-hard for this proof format is universal expansion, even expansion on a ... more >>>

TR18-178 | 9th October 2018
Leroy Chew

Hardness and Optimality in QBF Proof Systems Modulo NP

Quantified Boolean Formulas (QBFs) extend propositional formulas with Boolean quantifiers. Working with QBF differs from propositional logic in its quantifier handling, but as propositional satisfiability (SAT) is a subproblem of QBF, all SAT hardness in solving and proof complexity transfers to QBF. This makes it difficult to analyse efforts dealing ... more >>>

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