Sledgehammer is a component of the Isabelle/HOL proof assistant that integrates external automatic theorem provers (ATPs) to discharge interactive proof obligations. As a safeguard against bugs, the proofs found by the external provers are reconstructed in Isabelle. Reconstructing complex arguments involves translating them to Isabelle’s Isar format, supplying suitable justifications for each step. Sledgehammer transforms the proofs by contradiction into direct proofs; it iteratively tests and compresses the output, resulting in simpler and faster proofs; and it supports a wide range of ATPs, including E, LEO-II, Satallax, SPASS, Vampire, veriT, Waldmeister, and Z3.
Blanchette, J. C., Böhme, S., Fleury, M., Smolka, S. J., & Steckermeier, A. (2016). Semi-intelligible Isar Proofs from Machine-Generated Proofs. Journal of Automated Reasoning, 155-200. https://doi.org/10.1007/s10817-015-9335-3