Gabriel Istrate, Adrian Craciun. Proof complexity and the LovaszKneser Theorem. In Proceedings of the 17th International Conference on Theory and Applications of Satisfiability Testing (SAT' 14), vol. 8561 , pp. 138153. Lecture Notes in Computer Science, Springer Verlag, 2014.
Abstract:
We investigate the proof complexity of a class of propositional formulas expressing a combinatorial principle known as the KneserLovasz Theorem. This is a family of propositional tautologies, indexed by an nonnegative integer parameter k that generalizes the Pigeonhole Principle (PHP, obtained for k=1).
We show, for all fixed k, 2^{Omega(n)} lower bounds on resolution complexity and exponential lower bounds for bounded depth Frege proofs. These results hold even for the more restricted class of formulas encoding Schrijver's strengthening of the KneserLovasz Theorem. On the other hand for the cases k=2,3 (for which combinatorial proofs of the KneserLovasz Theorem are known) we give polynomial size Frege (k=2), respectively extended Frege (k=3) proofs. The paper concludes with a brief discussion of the results (that will be presented in a subsequent paper) on the complexity of the general case of the KneserLovasz theorem.
A free preliminary version is available at http://arxiv.org/abs/1402.4338
Keywords:
combinatorial topology, resolution complexity, Frege proofs
URL:
http://link.springer.com/chapter/10.1007/9783319092843_11
Posted by
Gabriel Istrate
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