Isabelle
Isabelle
(theory, tool)A system of type classes allows polymorphic object-logicswith overloading and automatic type inference.
Isabelle supports first-order logic - constructive andclassical versions; higher-order logic, similar to Gordon'sHOL; Zermelo Fr?nkel set theory; an extensional versionof Martin L?f's type theory, the classical first-ordersequent calculus, LK; the modal logics T, S4, andS43; and Logic for Computable Functions.
An object logic's syntax and inference rules are specifieddeclaratively allowing single-step proof construction.Proof procedures can be expressed using "tactics" and"tacticals". Isabelle provides control structures forexpressing search procedures and generic tools such assimplifiers and classical theorem provers which can be appliedto object-logics. Isabelle is built on top of Standard MLand uses its user interface.
http://cl.cam.ac.uk/Research/HVG/Isabelle/.
Mailing list: isabelle-users@cl.cam.ac.uk.