Prof. Dr. Peter Padawitz peter@ls5.cs.uni-dortmund.de
Tue, 08 Oct 2002 21:43:05 +0200

Expander2: A Formal Methods Presenter and Animator

Expander2 has been designed as a multi-purpose workbench for interactive
logical inference, constraint solving, data flow analysis and other
procedures building up proofs or computation sequences. Moreover,
several interpreters translate expressions into tailor-made
two-dimensional representations that range from trees and term graphs to
tables, fractals or other turtle-system-generated pictures.

Expander2 has been implemented in O'Haskell}, an extension of
Haskell with object-oriented features for reactive programming and a
typed interface to Tcl/Tk for developing GUIs. Besides a comfortable GUI
the design goals of Expander2 were to integrate testing, proving and
visualizing deductive methods, to admit several degrees of interaction
and to keep the system open for extensions or adaptations of individual
components to changing demands.

Proofs and computations performed with Expander2 follow the rules and
the semantics of swinging types
Swinging types combine constructor-based visible types with state-based
hidden types and have unique (Herbrand) models, which interpret
relations as the least or greatest solutions of their axioms.

All features of the system and their use are described in the manual


(sorry, this is still a big file, it will be splitted soon; PostScript
version: ../Expander2/Expander2.ps.gz). The paper
../Expander2/Chiemsee.ps.gz concentrates on the prover features.
Download everything with ../Expander2.tar.gz.

Please email comments, bugs, etc. to peter.padawitz@udo.edu.