There has been tremendous progress in the past decade in the field of quantified Boolean formulas (QBF), both in practical solving as well as in creating a theory of corresponding proof systems and their proof complexity analysis. Both for solving and for proof complexity, it is important to have interesting ... more >>>

We propose a new definition of the class of search problems that correspond to BPP.
Specifically, a problem in this class is specified by a polynomial-time approximable function $q:\{0,1\}^*\times\{0,1\}^*\to[0,1]$ that associates, with each possible solution $y$ to an instance $x$, a quality $q(x,y)$.
Intuitively, quality 1 corresponds to perfectly ... more >>>

In this paper we study syntactic branching programs of bounded repetition
representing CNFs of bounded treewidth.
For this purpose we introduce two new structural graph
parameters $d$-pathwidth and clique preserving $d$-pathwidth denoted
by $pw_d(G)$ and $cpw_d(G)$ where $G$ is a graph.
We show that $cpw_2(G) \leq O(tw(G) \Delta(G))$ ... more >>>