Quantifier Elimination by Dependency Sequents
arXiv:1201.5653
Abstract
We consider the problem of existential quantifier elimination for Boolean formulas in Conjunctive Normal Form (CNF). We present a new method for solving this problem called Derivation of Dependency-Sequents (DDS). A Dependency-sequent (D-sequent) is used to record that a set of quantified variables is redundant under a partial assignment. We introduce a resolution-like operation called join that produces a new D-sequent from two existing D-sequents. We also show that DDS is compositional, i.e. if our input formula is a conjunction of independent formulas, DDS automatically recognizes and exploits this information. We introduce an algorithm based on DDS and present experimental results demonstrating its potential.
arXiv commentAll the changes we made with respect to the previous versions are listed in the footnotes. The main change is that we modified the definition of a D-sequent using the notion of scoped redundancy of variables. We modified a few proofs of propositions affected by this change