<theory, tool> A generic theorem prover with support for several object-logics, developed by Lawrence C. Paulson <Larry.Paulson@cl.cam.ac.uk> in collaboration with {Tobias Nipkow (http://in.tum.de/Isabellenipkow/)} at the {Technical University of Munich}. A system of type classes allows polymorphic object-logics with overloading and automatic type inference. Isabelle supports first-order logic - constructive and classical versions; higher-order logic, similar to Gordon's HOL; Zermelo Frankel set theory; an extensional version of Martin Lof's type theory, the classical first-order sequent calculus, LK; the modal logics T, S4, and S43; and Logic for Computable Functions. An object 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. Isabelle/">http://cl.cam.ac.uk/Research/HVG/Isabelle/. Mailing list: isabelle-users@cl.cam.ac.uk. ["tactics"? "tacticals"?] (1999-07-26)

ISABELLE (also known later as Colliding Beam Accelerator, CBA) was a 200+200 GeV proton–proton colliding beam particle accelerator partially built by the United States government at Brookhaven National Laboratory in Upton, New York, before it was cancelled in July, 1983.

Isabelle of France (March 1224The Chronicon Turonense records the birth in 1224 "mense martio" of "Isabellis, filia Ludovici Regis Franciae". Chronicon Turonense, Recueil des historiens des Gaules et de la France, vol.