Imogen: Focusing the Polarized Inverse Method for Intuitionistic Propositional Logic

In this paper we describe Imogen, a theorem prover for intuitionistic propositional logic using the focused inverse method. We represent fine-grained control of the search behavior by polarizing the input formula. In manipulating the polarity of atoms and subformulas, we can often improve the search time by several orders of magnitude. We tested our method against seven other systems on the propositional fragment of the ILTP library. We found that our prover outperforms all other provers on a substantial subset of the library.