Seminars

Speaker: Alexis de Colnet (www.ac.tuwien.ac.at/people/decolnet/)

Title: An FPRAS for #NFA and #nFBDD

Abstract:

#NFA is the problem of counting the words of a given length accepted by
a non-deterministic finite automaton (NFA). The problem is #P-hard but
the approximate variant admits polynomial-time randomized algorithms
(FPRAS, or fully-polynomial time randomized approximation schemes).
Arenas, Croquevielle, Jayaram and Riveros were the first to show that
#NFA admits an FPRAS and that this result extends to several other
counting problems, in fact all problems in the class SpanL. In this talk
we present another FPRAS for #NFA which applies to problems not covered
by Arenas et al.'s result. In particular, the FPRAS described in this
talk can be used for the problem of counting the satisfying assignments
of non-deterministic read-once branching programs (nFBDD).