Isabelle
Isabelle is a generic proof assistant and interactive theorem prover used for formal verification of mathematical proofs and software systems. It provides a framework for constructing and checking formal proofs in various logical systems, with a focus on higher-order logic. The tool is widely used in academia and industry for verifying the correctness of hardware, software, and mathematical theories.
Developers should learn Isabelle when working on safety-critical systems, formal methods research, or mathematical verification projects where rigorous proof of correctness is required. It is particularly valuable in domains like aerospace, automotive, and security, where errors can have severe consequences, and in academic settings for teaching and advancing formal logic.