From MBQI to Enumerative Instantiation and Back

This work investigates the relation between model-based quantifier instantiation (MBQI) and enumerative instantiation (EI) in Satisfiability Modulo Theories (SMT). MBQI operates at the semantic level and guarantees to find a counterexample to a given a non-model. However, it may lead to weak instantiations. In contrast, EI strives for completeness by systematically enumerating terms at the syntactic level. However, such terms may not be counter-examples. Here we investigate the relation between the two techniques and report on our initial experiments of the proposed algorithm that combines the two.