This is Version 2.1.8 of the package AtlasRep written for GAP 4, whose aim is to provide an interface between GAP and databases such as the Atlas of Group Representations, which is available independent of GAP; it comprises representations of many almost simple groups and information about their maximal subgroups.

The AtlasRep package consists of this database and a GAP interface. The latter allows the user to get an overview of the database, and to access the data in GAP format.

There is a manual (available in HTML and pdf format) that describes the available functions in detail.

The package requires GAP 4.11.0 (or a newer version of GAP).


An overview of new features in the newest released version can be found in Section "What's New in AtlasRep" of the package manual.

The bibliographies in the Atlas of Finite Groups and in the Atlas of Brauer Characters are available online, in the subdirectory bibl.

For updating the table of contents of the core data, one can copy the file atlasprm.json to the directory pkg/atlasrep of the GAP installation.

An overview of the Atlas data currently available via the GAP interface can be found in the file htm/data/overview.htm.

A list of changes of server data describes which files have been changed in the meantime. It is thought mainly for documenting bugfixes in the part of the ATLAS of Group Representations that can be accessed via the GAP interface.


The data files of the ATLAS of Group Representations have been prepared by Robert Wilson, Peter Walsh, Jonathan Tripp, Ibrahim Suleiman, Richard Parker, Simon Norton, Simon Nickerson, Steve Linton, John Bray, and Rachel Abbott (in reverse alphabetical order).

The GAP interface was written by Thomas Breuer and Simon Nickerson.


If you have used the AtlasRep package to solve a problem then please send a short email to Robert Wilson or Thomas Breuer about it.

Any comments about the package are very welcome. If you have found important features missing or if there is a bug, let us know and we will try to address it in the next version of the package. Messages concerning the data of the package should be sent to Robert Wilson, messages concerning the GAP interface to Thomas Breuer.


If you want to get the newest version of the AtlasRep package then download the gzipped tar archive (ca. 2200k). Further information is contained in the file.

(The file and the archives are available also on the GAP servers.)

Note that the package archives do NOT contain the database part of the package; the GAP interface accesses the data on demand via the internet.

Here is a starter archive in gzipped tar format (ca. 22M) containing many small representations and programs. (Copy it into the pkg directory of the GAP installation, and unpack it there.)

The current table of contents of the core data is contained in the files atlasprm.json (ca. 750k, with checksums w.r.t. GAP's CrcFile function ) and atlasprm_SHA.json (ca. 1355k, with checksums in SHA256 format).

Up to version 1.5.1 of the package, the data format of the table of contents file was different, in particular no checksums were stored in it. The old format is available at OLD/atlasprm.g (ca. 500k).

Related Links

[Atlas Home] [GAP Home] [Atlas Bibliographies]


Thomas Breuer gratefully acknowledges support by the German Research Foundation (DFG) – Project-ID 286237555 – within the SFB-TRR 195 Symbolic Tools in Mathematics and their Applications.

File created on 11-Nov-2000 by Thomas Breuer.
Last modified on 03-Jan-2024 by Thomas Breuer.