The Isabelle System Distribution

Version information

This is the internal repository version of Isabelle. Starting with Isabelle98, the current line of Isabelle development introduces many new features, but also some incompatibilities with Isabelle94-XX. See the NEWS file in the distribution for more details.

System requirements

Isabelle requires a real Unix box with sufficient resources. Fun starts at about 32-64 MB of main memory (somewhat depending on your ML system), with several tens of MB disk space and a decent CPU. Speaking by today's hardware standards, even a rather low-end Linux box should make a nice platform for Isabelle.

Furthermore, Isabelle needs the following software, which is not part of the distribution:

The following ML system and platform combinations are known to work very well:

SML/NJ needs lots of store and disk space, but it is free. The current official release is 110 (there is an RPM archive available for Linux/x86). We still support the old 0.93 release, but do not recommend to use it.

MLWorks is a commercial ML programming environment. Isabelle on MLWorks 2.0 works well. It is about 20% faster than on SML/NJ while using slightly less memory and disk space. A few minor features (e.g. ML top-level pretty printing) are not yet supported, though.

Poly/ML used to be a commercial product by Abstract Hardware Limited (now Abstract, Inc.). It is no longer available. We're awaiting news about future availability of Poly/ML.


See file INSTALL in the Isabelle sources on how to build the system. Further background information may be found in the Isabelle System Manual, distributed with the sources (see directory doc).


The distribution includes only a very primitive interface based on ordinary terminal sessions.

Isamode by David Aspinall is a more elaborate interface for Isabelle. It runs under recent versions of XEmacs and is useful to both novices and experts.

Proof General is a generic Emacs interface for proof assistants, including Isabelle (as of version 2.0). Proof General is suitable for use by pacifists and Emacs militants alike. Its most prominent feature is script management, providing a metaphor of live proof script editing.

Other sources of information

Mailing list

The electronic mailing list provides a forum for Isabelle users to discuss problems and exchange information. To join, send a message to

Personal mail

Lawrence C Paulson
Computer Laboratory
University of Cambridge
Pembroke Street
Cambridge CB2 3QG

Phone: +44-223-334600
Fax: +44-223-334748


Tobias Nipkow
Institut fuer Informatik
T. U. Muenchen
D-80290 Muenchen

Phone: +49-89-289-22690
Fax: +49-89-289-28183

Please report any problems you encounter. While we shall try to be helpful, we can accept no responsibility for the deficiencies of Isabelle and their consequences.