In a semantic resolution proof we operate with clauses only
but allow {\em arbitrary} rules of inference:

C_1 C_2 ... C_m
__________________
C

Consistency is the only requirement. We prove a very simple
exponential lower bound for the size ... more >>>

Having good algorithms to verify tautologies as efficiently as possible
is of prime interest in different fields of computer science.
In this paper we present an algorithm for finding Resolution refutations
based on finding tree-like Res(k) refutations. The algorithm is based on
the one of Beame and Pitassi \cite{BP96} ... more >>>

We prove a quasi-polynomial lower bound on the size of bounded-depth
Frege proofs of the pigeonhole principle $PHP^{m}_n$ where
$m= (1+1/{\polylog n})n$.
This lower bound qualitatively matches the known quasi-polynomial-size
bounded-depth Frege proofs for these principles.
Our technique, which uses a switching lemma argument like other lower bounds
for ... more >>>

One of the major open problems in proof complexity is to prove lower bounds on $AC_0[p]$-Frege proof
systems. As a step toward this goal Impagliazzo, Mouli and Pitassi in a recent paper suggested to prove
lower bounds on the size for Polynomial Calculus over the $\{\pm 1\}$ basis. In this ... more >>>

The propositional proof system Sherali-Adams (SA) has polynomial-size proofs of the pigeonhole principle (PHP). Similarly, the Nullstellensatz (NS) proof system has polynomial size proofs of the bijective (i.e. both functional and onto) pigeonhole principle (ofPHP). We characterize the strength of these algebraic proof systems in terms of Boolean proof systems ... more >>>

We study Frege proofs for the one-to-one graph Pigeon Hole Principle
defined on the $n\times n$ grid where $n$ is odd.
We are interested in the case where each formula
in the proof is a depth $d$ formula in the basis given by
$\land$, $\lor$, and $\neg$. We prove that ... more >>>

The complexity class PPP contains all total search problems many-one reducible to the PIGEON problem, where we are given a succinct encoding of a function mapping n+1 pigeons to n holes, and must output two pigeons that collide in a hole. PPP is one of the “original five” syntactically-defined subclasses ... more >>>

The generalized pigeonhole principle says that if tN + 1 pigeons are put into N holes then there must be a hole containing at least t + 1 pigeons. Let t-PPP denote the class of all total NP-search problems reducible to finding such a t-collision of pigeons. We introduce a ... more >>>

The concept of redundancy in SAT lead to more expressive and powerful proof search techniques, e.g. able to express various inprocessing techniques, and to interesting hierarchies of proof systems [Heule et.al’20, Buss-Thapen’19].
We propose a general way to integrate redundancy rules in MaxSAT, that is we define MaxSAT variants of ... more >>>