We announce the availability of a Java application for storage and display
of finitely presented categories and functors among them.

The application is available for download at
http://mathcs.mta.ca/research/rosebrugh/gdct/
and is also linked from
http://www.mta.ca/~rrosebru/

For Win9x/NT users, a single download provides the application along with
the required Java run-time environment. Installation is via InstallShield.
For other operating systems, download the Java archive for the application
and, separately, the appropriate Java run-time environment (to which
links are provided).

We are interested in any response from users, and in expanding the
database of categories and functors available from the default server, so
we would be happy to receive examples from users. It is intended to
upgrade the application this summer, and so we would also appreciate
receiving any reports of difficulties in function or usability, as well as
suggestions for new functionality.

The application allows for the creation, editing, display and storage of
finitely presented categories. Categories can be opened and saved from
local files as well as loaded from a specified server. Open categories can
be displayed graphically, and the graphical display can be manipulated (in
3 dimensions) and stored. Several tools for testing properties of objects
and arrows can be applied; in this version they include Make Confluent,
Equality of Composities, Make Dual, Initial Object, and Terminal Object.

Functors between stored categories can also be created and stored. Open
functors can be displayed and animated.

A built-in help system describes how to use the application.

Graphical Database for Category Theory was developed in the summer of 1999
by Jeremy Bradbury and R. Rosebrugh with support from an NSERC Canada
undergraduate summer research assistantship.

Some of the algorithms used in GDCT were originally developed in A
Database of Categories, a C program written by Ryan Gunther and Michael
Fleming, and Category Theory Database Tools a Java applet, written by
Jeremy Bradbury, both under the supervision of R. Rosebrugh.

We hope that some of you will find GDCT useful and enjoyable.

Bob Rosebrugh and Jeremy Bradbury