English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We investigate the proof complexity of a class of propositional formulas expressing a combinatorial principle known as the Kneser-Lov\'{a}sz Theorem. This is a family of propositional tautologies, indexed by an nonnegative integer parameter $k$ that generalizes the Pigeonhole Principle (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 strenghtening of the Kneser-Lov\'{a}sz Theorem. On the other hand for the cases $k=2,3$ (for which combinatorial proofs of the Kneser-Lov\'{a}sz Theorem are known) we give polynomial size Frege ($k=2$), respectively extended Frege ($k=3$) proofs. The paper concludes with a brief announcement of the results (presented in subsequent work) on the proof complexity of the general case of the Kneser-Lov\'{a}sz theorem.

Proof Complexity and the Kneser-Lovász Theorem