Complete and Efficient Higher-Order Reasoning via Lambda-Superposition.

Superposition is a highly successful proof calculus for reasoning about first-order logic with equality. We present λ-superposition, which extends superposition to higher-order logic. Its design goals include soundness, completeness, efficiency, and gracefulness with respect to standard first-order superposition. The calculus is implemented in two automatic theorem provers: E and Zipper position. These provers regularly win trophies at the CADE ATP System Competition, confirming the calculus's applicability. This paper is a summary of research that took place between 2017 and 2022.