Iterative abstraction using SAT-based BMC with proof analysis

Variable Minimal Unsatisfiability

“…In abstraction refinement of model checking [2,3,4,5], the abstract model grows larger after refinement, which potentially prohibits the success of model checking for an enormous state space. The abstraction for next iteration is constructed by identification of an unsatisfiable core to rule out its spurious counterexamples.…”

Verification of Embedded Memory Systems using Efficient Memory Modeling

“…An abstract model is then generated for depth i by converting those latches in the given design that are not in the set LR i to pseudo-primary inputs. Due to the sufficiency property of U_Core, the resulting abstract model is guaranteed to preserve correctness of the property up to depth i [9,10]. Depending on locality of the property, the set LR i can be significantly smaller than the total latches in the given design.…”

“…This procedure simply retraces the resolution-based proof tree used by the SAT solver and identifies a subset formula that is sufficient for unsatisfiability [9,20]. One can then use either a gate-based abstraction [9] or a latch-based abstraction [10] technique to obtain an abstract model from the U_Core. Here we show a latch-based abstraction technique in line 11, to obtain a set of latch reasons LR i at depth i.…”

“…Note that after every iterative refinement step, the model size increases, making it increasingly difficult to verify. In contrast, abstraction-based approaches [9,10] use proof-based abstraction (PBA) techniques on a concrete design. As shown in [10], iterative abstraction can be used to apply such techniques on progressively more abstract models, thereby leading to significant reduction in model size.…”

“…In contrast, abstraction-based approaches [9,10] use proof-based abstraction (PBA) techniques on a concrete design. As shown in [10], iterative abstraction can be used to apply such techniques on progressively more abstract models, thereby leading to significant reduction in model size. However, since these approaches use the concrete model to start with, it may not be feasible to apply them on designs with large memories.…”