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We consider the extension of Boolean circuits to quantified Boolean circuits by adding universal and existential quantifier nodes with semantics adopted from quantified Boolean formulas (QBF). The concept allows not only prenex representations of the form ∀x1∃y1...∀xn∃yn c where c is an ordinary Boolean circuit with inputs x1,. We also consider more general(More)
In this paper, quantified Horn formulas (QHORN) are investigated. We prove that the behavior of the existential quantifiers depends only on the cases where at most one of the universally quantified variables is zero. Accordingly, we give a detailed characterization of QHORN satisfiability models which describe the set of satisfying truth assignments to the(More)
For propositional formulas we present a new transformation into satisfiability equivalent 3-CNF formulas of linear length. The main idea is to represent formulas as parallel-serial graphs. This is a subclass of directed acyclic multigraphs where the edges are labeled with literals and the AND operation (respectively, the OR operation) is expressed as(More)
In this paper, we consider the problem of compactly representing nested instantia-tions of propositional subformulas with different arguments as quantified Boolean formulas (QBF). We develop a generic QBF encoding pattern which combines and generalizes existing QBF encoding techniques for simpler types of redundancy. We obtain an equivalence-preserving(More)