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(theory, tool)
A generic theorem prover with support for several object-logics, developed by Lawrence C. Paulson <> in collaboration with Tobias Nipkow 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 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; 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.

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This article is provided by FOLDOC - Free Online Dictionary of Computing (
References in classic literature ?
Those who can read German will find an excellent guide, in this respect, in Frau Foerster-Nietzsche's exhaustive and highly interesting biography of her brother: "Das Leben Friedrich Nietzsche's" (published by Naumann); while the works of Deussen, Raoul Richter, and Baroness Isabelle von Unger- Sternberg, will be found to throw useful and necessary light upon many questions which it would be difficult for a sister to touch upon.
I remember, before entering the park, I stood awhile to contemplate the statue of General Belliard, and then I advanced to the top of the great staircase just beyond, and I looked down into a narrow back street, which I afterwards learnt was called the Rue d'Isabelle. I well recollect that my eye rested on the green door of a rather large house opposite, where, on a brass plate, was inscribed, "Pensionnat de Demoiselles." Pensionnat!
I have ruined myself, my friend, ruined myself for the restoration of this young prince who has just passed, cantering on his isabelle colored horse."
French actress Isabelle Huppert received Honorary Heart of Sarajevo Award for her exceptional contribution to the art of film at a ceremony in National Theater last night at the 25th Sarajevo Film Festival.
Actress and mental health advocate Isabelle Daza has launched on Instagram TV a series educating her followers about mental illnesses, anxiety, and depression.
aunching her eponymous brand 15 years ago, couture designer Isabelle Randall handcrafts bridalwear and eveningwear in her Aberdeen atelier.
The news of baby Isabelle's arrival was one of the last things Nick ever whispered to his wife before she died.
Recently, teenager Isabelle Carnell-Holdaway, who was fighting a serious infection with a resistant bug, was helped by "phage" therapy, which might be a powerful tool in fighting bacterial resistance.
Among this year's recipients was nine-yearold Isabelle Curno, from Maud in Aberdeenshire.
Sisters Isabelle and Ava Daza traveled to Italy for some private time with loved ones, as well as to rest and recuperate.
Isabelle Mary Hoffman ARLINGTON HEIGHTS Isabelle Mary Hoffman was born on June 27, 1939 in Chicago, Illinois to Pat and Isabelle (nee Gillio) Perrone.