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Electronic Colloquium on Computational Complexity

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All reports by Author Nicola Galesi:

TR21-022 | 20th February 2021
Stefan Dantchev, Nicola Galesi, Abdul Ghani, Barnaby Martin

Depth lower bounds in Stabbing Planes for combinatorial principles

We prove logarithmic depth lower bounds in Stabbing Planes for the classes of combinatorial principles known as the Pigeonhole principle and the Tseitin contradictions. The depth lower bounds are new, obtained by giving almost linear length lower bounds which do not depend on the bit-size of the inequalities and in ... more >>>

TR19-069 | 6th May 2019
Nicola Galesi, Dmitry Itsykson, Artur Riazanov, Anastasia Sofronova

Bounded-depth Frege complexity of Tseitin formulas for all graphs

Revisions: 1

We prove that there is a constant $K$ such that \emph{Tseitin} formulas for an undirected graph $G$ requires proofs of
size $2^{\mathrm{tw}(G)^{\Omega(1/d)}}$ in depth-$d$ Frege systems for $d<\frac{K \log n}{\log \log n}$, where $\tw(G)$ is the treewidth of $G$. This extends H{\aa}stad recent lower bound for the grid graph ... more >>>

TR19-052 | 9th April 2019
Nicola Galesi, Leszek Kolodziejczyk, Neil Thapen

Polynomial calculus space and resolution width

We show that if a $k$-CNF requires width $w$ to refute in resolution, then it requires space $\sqrt w$ to refute in polynomial calculus, where the space of a polynomial calculus refutation is the number of monomials that must be kept in memory when working through the proof. This is ... more >>>

TR18-170 | 4th October 2018
Nicola Galesi, Navid Talebanfard, Jacobo Toran

Cops-Robber games and the resolution of Tseitin formulas

We characterize several complexity measures for the resolution of Tseitin formulas in terms of a two person cop-robber game. Our game is a slight variation of the one Seymour and Thomas used in order to characterize the tree-width parameter. For any undirected graph, by counting the number of cops needed ... more >>>

TR18-165 | 20th September 2018
Stefan Dantchev, Nicola Galesi, Barnaby Martin

Resolution and the binary encoding of combinatorial principles

We investigate the size complexity of proofs in $RES(s)$ -- an extension of Resolution working on $s$-DNFs instead of clauses -- for families of contradictions given in the {\em unusual binary} encoding. A motivation of our work is size lower bounds of refutations in Resolution for families of contradictions in ... more >>>

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