SEChecker: A Sequential Equivalence Checking Framework Based on ${K}$th Invariants

In recent years, considerable research efforts have been devoted to utilizing circuit structural information to improve the efficiency of Boolean satisfiability (SAT) solving, resulting in several efficient circuit-based SAT solvers. In this paper, we present a sequential equivalence checking framework based on a number of circuit-based SAT solving techniques as well as a novel invariant checker. We first introduce the notion of $k$th invariants. In contrast to the traditional invariants that hold for all cycles, $k$ th invariants are guaranteed to hold only after the $k$th cycle from the initial state. We then present a bounded model checker (BMChecker) and an invariant checker (IChecker), both of which are based on circuit SAT techniques. Jointly, BMChecker and IChecker are used to compute the $k$th invariants, and are further integrated in a sequential circuit SAT solver for checking sequential equivalence. Experimental results demonstrate that the new sequential equivalence checking framework can efficiently verify large industrial designs that cannot be verified by existing solutions.