<theory, tool> Lawrence C. Paulson <Larry.Paulson@cl.cam.ac.uk>'s generic theorem prover with support for several object-logics: first-order logic, constructive and classical versions; higher-order logic, similar to Gordon's HOL; Zermelo Fr�nkel set theory; an extensional version of Martin L�f's type theory, the classical first-order sequent calculus, LK; the modal logics T, S4 and S43; Logic for Computable Functions.
A logic's syntax and inference rules are specified declaratively allowing single-step proof construction. Proof procedures can be expressed using tactics and tacticals. Isabelle provides control structures for expressing search procedures and generic tools such as simplifiers and classical theorem provers which can be applied to object-logics. Isabelle is built on top of Standard ML and uses its user interface.
The latest version, Isabelle-93, is significantly faster than Isabelle-92 and has several other improvements.
Mailing list: isabelle-users@cl.cam.ac.uk.
(20 Dec 1993)