SAT-Inspired Higher-Order Eliminations

We generalize several propositional preprocessing techniques to higher-order logic, building on existing first-order generalizations. These eliminate literals, clauses, or predicate symbols from the problem, with aim of making it more amenable automatic proof search. also introduce a new technique, which we call quasipure literal elimination, that strictly subsumes pure elimination. The are implemented in Zipperposition theorem prover. Our evaluation shows they sometimes help prove problems originating Isabelle formalizations and TPTP library.