Search Results for author: Igor Razgon

Found 5 papers, 0 papers with code

Tree-width dichotomy

no code implementations2 Dec 2020 Vadim Lozin, Igor Razgon

We prove that the tree-width of graphs in a hereditary class defined by a finite set $F$ of forbidden induced subgraphs is bounded if and only if $F$ includes a complete graph, a complete bipartite graph, a tripod (a forest in which every connected component has at most 3 leaves) and the line graph of a tripod.

Combinatorics Discrete Mathematics

Non-FPT lower bounds for structural restrictions of decision DNNF

no code implementations25 Aug 2017 Andrea Calì, Florent Capelli, Igor Razgon

We give a non-FPT lower bound on the size of structured decision DNNF and OBDD with decomposable AND-nodes representing CNF-formulas of bounded incidence treewidth.

On oblivious branching programs with bounded repetition that cannot efficiently compute CNFs of bounded treewidth

no code implementations10 Oct 2015 Igor Razgon

In this paper we study complexity of an extension of ordered binary decision diagrams (OBDDs) called $c$-OBDDs on CNFs of bounded (primal graph) treewidth.

On the read-once property of branching programs and CNFs of bounded treewidth

no code implementations2 Nov 2014 Igor Razgon

In this paper we prove a space lower bound of $n^{\Omega(k)}$ for non-deterministic (syntactic) read-once branching programs ({\sc nrobp}s) on functions expressible as {\sc cnf}s with treewidth at most $k$ of their primal graphs.

Negation

Soft Constraints of Difference and Equality

no code implementations16 Jan 2014 Emmanuel Hebrard, Dániel Marx, Barry O'Sullivan, Igor Razgon

Moreover, we show that the maximum number of pairs of equal variables can be approximated by a factor 1/2 with a linear time greedy algorithm.

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