
<!-- %W  introduc.xml    GAP 4 package AtlasRep             Thomas Breuer -->
<!-- %Y  Copyright 2001, Lehrstuhl D für Mathematik, RWTH Aachen, Germany -->


<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Chapter Label="chap:introduc">
<Heading>Introduction to the <Package>AtlasRep</Package> Package</Heading>

The aim of the &GAP;&nbsp;4 package <Package>AtlasRep</Package> is to provide
a link between &GAP; and the <Q>&ATLAS; of Group Representations</Q>,
a database that comprises generating permutations and matrices
for many almost simple groups,
and information about their maximal subgroups.
This database is available independent of &GAP; at

<P/>
&ATLASSERVER;
<P/>

The <Package>AtlasRep</Package> package consists of this database
(see Section&nbsp;<Ref Sect="sect:An Atlas of Group Representations"/>)
and a &GAP; interface
(see Section&nbsp;<Ref Sect="sect:The GAP Interface to the Atlas of Group Representations"/>);
the latter is extended by further information available via the internet
(see Section&nbsp;<Ref Sect="sect:Web Services for the AtlasRep Package"/>).

<P/>

This package manual has the following parts.

<List>
<Mark>A tutorial</Mark>
<Item>
    gives an overview how the functions of the package
    can be used, see Chapter&nbsp;<Ref Chap="chap:tutorial"/>.
</Item>
<Mark>User interface functions</Mark>
<Item>
    are described in 
    Chapter&nbsp;<Ref Chap="chap:The User Interface of the AtlasRep Package"/>.
</Item>
<Mark>Customizations of the package</Mark>
<Item>
    are described in Chapter&nbsp;<Ref Chap="chap:atlasrep"/>.
</Item>
<Mark>Information how to extend the database</Mark>
<Item>
    can be found in Chapter&nbsp;<Ref Chap="chap:Private Extensions"/>.
</Item>
<Mark>More technical information</Mark>
<Item>
    can be found in the chapters&nbsp;<Ref Chap="chap:utilities"/>
    (concerning &GAP; objects that are introduced by the package)
    and&nbsp;<Ref Chap="chap:Technicalities of the AtlasRep Package"/>
    (concerning global variables and sanity checks).
</Item>
</List>


<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Section Label="sect:An Atlas of Group Representations">
<Heading>The &ATLAS; of Group Representations</Heading>

The &ATLAS; of Group Representations consists of matrices over various rings,
permutations, and shell scripts encoding so-called black box programs
<Index>black box program</Index>
(see <Cite Key="Nic06"/>
and Section&nbsp;<Ref Sect="sect:Black Box Programs"/>).
Many of these scripts are straight line programs
<Index>straight line program</Index>
(see&nbsp;<Cite Key="BSW01"/>, <Cite Key="SWW00"/>,
and&nbsp;<Ref Sect="Straight Line Programs" BookName="ref"/>)
and straight line decisions
(see Section&nbsp;<Ref Sect="sect:Straight Line Decisions"/>).
These programs can be used to compute certain elements in a group <M>G</M>
from its standard generators
(see&nbsp;<Cite Key="Wil96"/>
and Section&nbsp;<Ref Sect="sect:Standard Generators Used in AtlasRep"/>)
for example generators of maximal subgroups of <M>G</M>
or representatives of conjugacy classes of <M>G</M>.

<P/>

The &ATLAS; of Group Representations has 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).

<P/>

The information was computed and composed using computer algebra systems
such as &MeatAxe; (see&nbsp;<Cite Key="Rin98"/>),
Magma (see&nbsp;<Cite Key="CP96"/>), and &GAP;
(in reverse alphabetical order).
<Index Key="MeatAxe">&MeatAxe;</Index>
<Index Key="Magma"><Package>Magma</Package></Index>
Part of the constructions have been documented in the literature on
almost simple groups, or the results have been used in such publications,
see for example the references in&nbsp;<Cite Key="CCN85"/>
and&nbsp;<Cite Key="BN95"/>.

<P/>

If you use the &ATLAS; of Group Representations to solve a problem then
please send a short email to&nbsp;&WILSONMAIL; about it.
The &ATLAS; of Group Representations database should be referenced
with the entry&nbsp;<Cite Key="AGR"/> in the bibliography of this manual.

<P/>

If your work made use of functions of the &GAP; interface
(see Section&nbsp;<Ref Sect="sect:The GAP Interface to the Atlas of Group Representations"/>)
then you should also reference this interface,
as follows.

<Listing>
@misc{ AtlasRep&VERSIONNUMBER;,
  author =       {Wilson, R. A. and Parker, R. A. and Nickerson, S. and
                  Bray, J. N. and Breuer, T.},
  title =        {{AtlasRep}, A \textsf{GAP} Interface to the Atlas of
                  Group Representations,
                  {V}ersion &VERSIONNUMBER;},
  month =        {&RELEASEMONTH;},
  year =         {&RELEASEYEAR;},
  note =         {Refereed \textsf{GAP} package},
  howpublished = {http://www.math.rwth-aachen.de/\~{}Thomas.Breuer/atlasrep}
}
</Listing>

<P/>

For referencing the &GAP; system in general,
use the entry&nbsp;<Cite Key="GAP4412"/> in the bibliography of this manual,
see also
<P/>
<URL>http://www.gap-system.org</URL>.

</Section>


<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Section Label="sect:The GAP Interface to the Atlas of Group Representations">
<Heading>The GAP Interface to the &ATLAS; of Group Representations</Heading>

<Index Key="C-MeatAxe"><C>C</C>-&MeatAxe;</Index>
The &GAP; interface to the &ATLAS; of Group Representations consists of
essentially two parts.

<List>
<Item>
  First, there is the <E>user interface</E>
  which allows the user to get an overview of the contents of the database,
  and to access the data in &GAP; format;
  this is described in
  Chapter&nbsp;<Ref Chap="chap:The User Interface of the AtlasRep Package"/>.
  Advanced users may add their own data to the database,
  this is described in Chapter&nbsp;<Ref Chap="chap:Private Extensions"/>.
</Item>
<Item>
  Second, there is <E>administrational information</E>,
  which covers also the declaration of &GAP; objects
  such as straight line decisions and black box programs.
  This is important mainly for users interested in the actual implementation
  (e.&nbsp;g., for modifying the package) or in using it together with the
  <C>C</C>-&MeatAxe; standalone (see&nbsp;<Cite Key="Rin98"/>);
  this is described in
  Chapter&nbsp;<Ref Chap="chap:Technicalities of the AtlasRep Package"/>.
</Item>
</List>

Information concerning the <C>C</C>-&MeatAxe;,
including the manual&nbsp;<Cite Key="Rin98"/>,
can be found at

<P/>
<URL>http://www.math.rwth-aachen.de/LDFM/homes/MTX</URL>
<P/>

<!-- A &GAP;&nbsp;4 Package that provides access to the functionality of the
C-&MeatAxe; is in preparation. -->

The interface and this manual have been provided by Thomas Breuer,
except for the interpreter for black box programs
(see Section&nbsp;<Ref Sect="sect:Black Box Programs"/>),
which is due to Simon Nickerson.
Comments, bug reports, and hints for improving the interface
can be sent to&nbsp;<Email>sam@math.rwth-aachen.de</Email>.
<!-- There is a reference to this statement in Chapter
     ``chap:The User Interface of the AtlasRep Package''. -->

</Section>


<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Section Label="sect:What's New in AtlasRep?">
<Heading>What's New in <Package>AtlasRep</Package>,
Compared to Older Versions?</Heading>

<!-- The section title is referenced in index.html. -->
<Alt Only="HTML"><![CDATA[<a id="sect:news"/>]]></Alt>
<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Subsection Label="sect:What's New in Version 1.5?">
<Heading>What's New in Version 1.5?</Heading>
 
<List>
<Item>
  The function
  <Ref Func="AtlasSubgroup"
   Label="for a group name (and various arguments) and a number"/>
  now admits also the return value
  of <Ref Func="OneAtlasGeneratingSetInfo"/> or the return value of
  <Ref Func="AtlasGroup" Label="for various arguments"/> as its first
  argument.
  The latter is implemented via the new attribute
  <Ref Attr="AtlasRepInfoRecord"/>, which is set in the groups constructed
  by <Ref Func="AtlasGroup" Label="for various arguments"/>.
</Item>
<Item>
  Information about transitivity, rank, primitivity, and point stabilizers
  of many permutation representations is now available.
  If applicable then this information appears in the records returned by
  <Ref Func="OneAtlasGeneratingSetInfo"/>,
  it is part of the overview shown by <Ref Func="DisplayAtlasInfo"/>,
  and it is shown also in the data overview in the web,
  see Section <Ref Sect="sect:Web Services for the AtlasRep Package"/>.
  <P/>
  Two new manual sections about point stabilizers have been added,
  see the sections
  <Ref Subsect="subsect:Example: Index 770 Subgroups in M22"/>
  and <Ref Subsect="subsect:Example: Index 462 Subgroups in M22"/>.
</Item>
<Item>
  Information about the characters afforded by many matrix and permutation
  representations is now available.
  If applicable then this information appears in the records returned by
  <Ref Func="OneAtlasGeneratingSetInfo"/>,
  for matrix representations it is part of the overview shown by
  <Ref Func="DisplayAtlasInfo"/>,
  and it is shown also in the data overview in the web,
  see Section <Ref Sect="sect:Web Services for the AtlasRep Package"/>.
</Item>
<Item>
  The functions <Ref Func="Character"
  Label="for a character table and a list" BookName="ref"/>,
  <Ref Func="Identifier" Label="for character tables" BookName="ref"/>,
  <Ref Func="IsPrimitive" BookName="ref"/>,
  <Ref Func="IsTransitive" BookName="ref"/>, 
  <Ref Func="Transitivity" BookName="ref"/>, and
  <Ref Func="RankAction" BookName="ref"/>
  are now supported as input conditions in
  <Ref Func="DisplayAtlasInfo"/>,
  <Ref Func="OneAtlasGeneratingSetInfo"/>, etc..
</Item>
<Item>
  It is now possible to restrict the data shown by
  <Ref Func="DisplayAtlasInfo"/> to private or non-private data.
  Also the data returned by <Ref Func="OneAtlasGeneratingSetInfo"/>
  can be restricted to private or non-private data.
</Item>
<Item>
  A tutorial for beginners was added to the manual,
  see Chapter <Ref Chap="chap:tutorial"/>,
  and the manual was restructured.
</Item>
<!--
<Item>
  Due to the omission of some consistency checks which are not necessary
  at runtime, loading the package needs less time now.
  (This could be improved further.)
</Item>
-->
<Item>
  In the overview shown by <Ref Func="DisplayAtlasInfo"/>
  and in the data overview in the web
  (see Section <Ref Sect="sect:Web Services for the AtlasRep Package"/>),
  the ordering of groups was improved such that, e.g.,
  <C>"A9"</C> precedes <C>"A10"</C>.
</Item>
<Item>
  The function <Ref Func="AtlasClassNames"/> now admits also a Brauer table
  as its argument, and works also for character tables of bicyclic extensions
  of simple groups.
</Item>
<Item>
  The group names that are entered in <Ref Func="DisplayAtlasInfo"/>,
  <Ref Func="OneAtlasGeneratingSetInfo"/>, etc., are now case insensitive,
  and if the package <Package>CTblLib</Package> is available then the
  admissible group names for the &GAP; character table of the group in
  question can be used in these functions.
</Item>
<Item>
  In order to reduce the number of global variables, several functions
  have been turned into components of the new global variable
  <Ref Var="AGR"/>.
  A few of these functions had been documented in the previous version,
  the old values are still available if the package file
  <F>gap/obsolete.g</F> has been read.
  This file is read automatically when the package gets loaded
  if <C>GAPInfo.UserPreferences.ReadObsolete</C> is <K>true</K>,
  see <Ref Subsect="The gap.ini file" BookName="ref"/>.
</Item>
<Item>
  A few nicer characters are used by <Ref Func="DisplayAtlasInfo"/>
  if <C>GAPInfo.TermEncoding</C> has the value <C>"UTF-8"</C> and if
  <C>AtlasOfGroupRepresentationsInfo.displayFunction</C> is different from
  <Ref Func="Print" BookName="ref"/>,
  see Section&nbsp;<Ref Subsect="subsect:Customizing DisplayAtlasInfo"/>.
</Item>
<Item>
  A bug in the function <Ref Func="ReloadAtlasTableOfContents"/> was fixed.
  Thanks to Jack Schmidt for reporting this bug.
</Item>
</List>

</Subsection>


<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Subsection Label="sect:What's New in Version 1.4?">
<Heading>What's New in Version 1.4?</Heading>
 
<List>
<Item>
  In addition to the group orders that were added in version 1.3
  (see Section <Ref Sect="sect:What's New in Version 1.3?"/>),
  also many orders of maximal subgroups are now available.
  These values occur in the records returned by <Ref Func="AtlasProgram"/>
  (for the case of <C>"maxes"</C> type programs)
  and of the three argument version of <Ref Func="AtlasGenerators"/>;
  now a <C>size</C> component may be bound.
  In these cases, the groups returned by
  <Ref Func="AtlasSubgroup" Label="for a group name (and various arguments) and a number"/>
  have the <Ref Attr="Size" BookName="ref"/> attribute set.
</Item>
<Item>
  The information about the number of maximal subgroups, if available,
  is now used in <Ref Func="DisplayAtlasInfo"/>.
</Item>
<Item>
  In many cases, straight line programs for computing generators of maximal
  subgroups of a group <M>G</M>, say, can in fact be used to compute also
  generators of maximal subgroups of downward extensions of <M>G</M>;
  if not then it may suffice to extend the given straight line programs by
  additional generators.
  <P/>
  Currently this yields more than <M>200</M> new possibilities to compute
  maximal subgroups, this means a growth by about <M>25</M> percent.
  For example, all maximal subgroups of <M>12.M_{22}</M> and <M>2.Fi_{22}</M>
  can now be accessed via <Ref Func="AtlasGenerators"/>.
  <P/>
  (Of course this extension means only that one can access the straight
  line programs in question automatically via the &GAP; interface.
  In principle one could have used them already before, by explicitly
  applying a straight line program for a factor group to generators of a
  group, and perhaps adding some element in the kernel of the natural
  epimorphism.)
  <P/>
  For this feature,
  information about the compatibility of standard generators of groups and
  their factor groups was added.
</Item>
<Item>
  The bibliographies contained in the &ATLAS; of Finite Groups
  <Cite Key="CCN85"/> and in the &ATLAS; of Brauer Characters
  <Cite Key="JLPW95"/> are now available,
  see <Ref Func="BrowseBibliographySporadicSimple"/>.
</Item>
<Item>
  <!-- changed handling of minimal degrees! -->
  If the &GAP; package <Package>Browse</Package>
  (see <Cite Key="Browse"/>) is loaded then the new functions
  <Ref Func="BrowseMinimalDegrees"/> and
  <Ref Func="BrowseBibliographySporadicSimple"/> are available;
  these functions can be called also by choosing the
  corresponding menu entries of the <Package>Browse</Package> application
  <Ref Func="BrowseGapData" BookName="Browse"/>.
</Item>
<Item>
  The function <Ref Func="AtlasGroup" Label="for various arguments"/>
  now admits also the return value of
  <Ref Func="OneAtlasGeneratingSetInfo"/> as its argument.
</Item>
</List>

</Subsection>


<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Subsection Label="sect:What's New in Version 1.3.1?">
<Heading>What's New in Version 1.3.1?</Heading>
 
This version was mainly released in order to fix a few problems.
Now one does not get warnings about unbound variables
when the package is loaded
and the &GAP; package <Package>IO</Package> <Cite Key="IO"/>
is not available,
and pathological situations in <Ref Func="FFMatOrPermCMtxBinary"/>
(concerning extremely short corrupted data files and different
byte orderings in binary files) are handled more carefully.

<P/>

Besides this, the two functions
<Ref Func="AtlasGroup" Label="for various arguments"/> and
<Ref Func="AtlasSubgroup" Label="for a group name (and various arguments) and a number"/> were introduced,
and the extended function <Ref Func="QuaternionAlgebra" BookName="ref"/>
of &GAP;&nbsp;4.4.10 can now be used for describing base rings in
<Ref Func="OneAtlasGeneratingSetInfo"/> and
<Ref Func="AllAtlasGeneratingSetInfos"/>.
(This is the reason why this version of the package requires at least
version 4.4.10 of &GAP;.)

</Subsection>


<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Subsection Label="sect:What's New in Version 1.3?">
<Heading>What's New in Version 1.3?</Heading>
 
<List>
<Item>
  The database was extended, see
  Section&nbsp;<Ref Subsect="subsect:Compressed or uncompressed data files"/>
  for the number and size of files.
</Item>
<Item>
  New data types and corresponding &GAP; objects have been introduced,
  for representing semi-presentations, presentations,
  and programs for finding standard generators.
  For details, see
  <Ref Func="AtlasProgram"/>,
  Chapter&nbsp;<Ref Chap="chap:utilities"/>, and
  Section&nbsp;<Ref Sect="sect:Filenames Used in the AGR"/>.
</Item>
<Item>
  The records returned by the functions <Ref Func="AtlasGenerators"/>,
  <Ref Func="OneAtlasGeneratingSetInfo"/>, and
  <Ref Func="AllAtlasGeneratingSetInfos"/>
  now contain the name and (if known) the order of the group in question,
  and also components describing the degree in the case of permutation
  representations
  or the dimension and the base ring of the natural module in the case of
  matrix representations.
</Item>
<Item>
  For many of the groups, information about the minimal degree of faithful
  permutation representations and the minimal dimensions of faithful matrix
  representations in various characteristics is available for
  <Ref Func="DisplayAtlasInfo"/>,
  <Ref Func="OneAtlasGeneratingSetInfo"/>, and
  <Ref Func="AllAtlasGeneratingSetInfos"/>,
  see also Section <Ref Sect="sect:Representations of Minimal Degree"/>.
  For these functions,
  also properties such as <Ref Func="IsPrimeInt" BookName="ref"/> can be used
  to describe the intended restriction of the output.
</Item>
<Item>
  One can now use <Ref Func="Pager" BookName="ref"/> functionality
  in <Ref Func="DisplayAtlasInfo"/>,
  see Section&nbsp;<Ref Subsect="subsect:Customizing DisplayAtlasInfo"/>.

  <P/>

  An interactive alternative to <Ref Func="DisplayAtlasInfo"/> is provided by
  the function <Ref Func="BrowseAtlasInfo" BookName="Browse"/> from the
  new (recommended) &GAP; package <Package>Browse</Package>
  <Cite Key="Browse"/>.
</Item>
<Item>
  The functions <Ref Func="OneAtlasGeneratingSetInfo"/> and
  <Ref Func="AllAtlasGeneratingSetInfos"/> now admit also
  a list of group names as the first argument.
</Item>
<Item>
  The functions for actually accessing the data are more flexible now, see
  Section&nbsp;<Ref Subsect="subsect:Customizing the Access to Data files"/>.
</Item>
<Item>
  For transferring remote data,
  the &GAP; package <Package>IO</Package> <Cite Key="IO"/>
  can now be used (and is recommended) as an alternative to <F>wget</F>,
  <Index Key="wget"><F>wget</F></Index>
  see
  Section&nbsp;<Ref Subsect="subsect:Accessing data files with wget or IO"/>.
</Item>
<Item>
  The address of the data server has changed.
  <Index Key="ftp"><F>ftp</F></Index>
  Since the access to the server is no longer possible via <F>ftp</F>,
  the mechanim used up to version 1.2, which was based on <F>ftp</F>,
  had to be rewritten.

  <P/>

  The main consequence of this change is that information about updates
  of the table of contents is now provided at the package's homepage.
  This means that on the one hand,
  now package users cannot <E>compute</E> the table of contents directly
  from the server data,
  but on the other hand the update information can be <E>downloaded</E>
  without the necessity to install <F>perl</F>.
  <Index Key="perl"><F>perl</F></Index>

  <P/>

  Another consequence is that the system program <F>ls</F> is no longer
  needed,
  see Section&nbsp;<Ref Subsect="sect:What's New in Version 1.1?"/>.
</Item>
<Item>
  The package manual has been restructured, extended and improved.
  It is now based on the package &GAPDoc; <Cite Key="GAPDoc"/>.
</Item>
</List>

</Subsection>


<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Subsection Label="sect:What's New in Version 1.2?">
<Heading>What's New in Version 1.2?</Heading>

Not much.

<P/>

The release of Version&nbsp;1.2 became necessary first of all
in order to provide a package version that is compatible with &GAP;&nbsp;4.4,
since some cross-references into the &GAP; Reference Manual were broken
due to changes of section names.
Additionally, several web addresses concerning the package itself
were changed and thus had to be adjusted.

<P/>

This opportunity was used
<List>
<Item>
    to upgrade the administrational part for
    loading the package to the mechanism that is recommended
    for &GAP;&nbsp;4.4,
</Item>
<Item>
    to extend the test suite, 
    which now covers more consistency checks using
    the &GAP; Character Table Library&nbsp;<Cite Key="CTblLib1.1.3"/>,
</Item>
<Item>
    to make the function <Ref Func="ScanMeatAxeFile"/> more robust,
    due to the fact that the &GAP; function
    <Ref Func="PermList" BookName="ref"/> now
    returns <K>fail</K> instead of raising an error,
</Item>
<Item>
    to change the way how representations with prescribed properties are
    accessed (the new function <Ref Func="OneAtlasGeneratingSetInfo"/> is now
    preferred to the former <C>OneAtlasGeneratingSet</C>,
    and <Ref Func="AllAtlasGeneratingSetInfos"/>
    has been added in order to provide programmatic access in parallel to the
    human readable descriptions printed by <Ref Func="DisplayAtlasInfo"/>),
</Item>
<Item>
    and last but not least to include the current table of contents of the
    underlying database.
</Item>
</List>

<P/>

For <Package>AtlasRep</Package> users,
the new feature of &GAP;&nbsp;4.4 is particularly
interesting that due to better kernel support, reading large matrices
over finite fields is now faster than it was in &GAP;&nbsp;4.3.

</Subsection>


<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Subsection Label="sect:What's New in Version 1.1?">
<Heading>What's New in Version 1.1?</Heading>

The biggest change w.r.t.&nbsp;Version&nbsp;1.1 is the addition of
private extensions
(see Chapter&nbsp;<Ref Chap="chap:Private Extensions"/>).
It includes a new <Q>free format</Q> for straight line programs
(see Section&nbsp;<Ref Sect="sect:Effect of Private Extensions"/>).
Unfortunately, this feature requires the system program <F>ls</F>,
so it may be not available for example under MS Windows operating systems.
[But see Section&nbsp;<Ref Subsect="sect:What's New in Version 1.3?"/>.]

<P/>

In order to admit the addition of other types of data,
the implementation of several functions has been changed.
Data types are described in
Section&nbsp;<Ref Sect="sect:Data Types Used in the AGR"/>.
An example of a new data type are quaternionic representations
(see Section&nbsp;<Ref Sect="sect:Filenames Used in the AGR"/>).
The user interface itself
(see Chapter&nbsp;<Ref Chap="chap:The User Interface of the AtlasRep Package"/>)
remained the same.

<P/>

<Index Key="wget"><F>wget</F></Index>
As an alternative to <C>perl</C>, one can use <C>wget</C> now
for transferring data files
(see&nbsp;<Ref Sect="sect:User Parameters for the AtlasRep Package"/>).

<P/>

Data files can be read much more efficiently in &GAP;&nbsp;4.3 than in
&GAP;&nbsp;4.2.
In Version&nbsp;1.1 of the <Package>AtlasRep</Package> package,
this feature is used for reading
matrices and permutations in &MeatAxe; text format with
<Ref Func="ScanMeatAxeFile"/>.
As a consequence, (at least) &GAP;&nbsp;4.3 is required for
<Package>AtlasRep</Package> Version&nbsp;1.1.

<P/>

<Index Key="gzip"><F>gzip</F></Index>
The new <C>compress</C> component of the global variable
<Ref Var="AtlasOfGroupRepresentationsInfo"/>
allows one to store data files automatically in <F>gzip</F>ped form.

<P/>

For matrix representations in characteristic zero, invariant forms and
generators for the centralizer algebra are now accessible in &GAP; if they
are contained in the source files --this information had been ignored in
Version&nbsp;1.0
(see&nbsp;<Ref
Func="AtlasOfGroupRepresentationsTestTableOfContentsRemoteUpdates"/>
for necessary updates).

<P/>

Additional information is now available via the internet
(see&nbsp;<Ref Sect="sect:Web Services for the AtlasRep Package"/>).

<P/>

The update facilities have been extended
(see&nbsp;<Ref Sect="sect:Maintaining the Local Data of the AtlasRep Package"/>).

<P/>

The manual is now distributed also in pdf and HTML format; on the other hand,
the PostScript format manual is no longer contained in the archives.

<P/>

Apart from these changes,
a few minor bugs in the handling of &MeatAxe; files have been fixed,
typos in the documentation have been corrected,
and the syntax checks for &ATLAS; straight line programs
(see&nbsp;<Ref Sect="sect:Reading and Writing Atlas Straight Line Programs"/>)
have been improved.

</Subsection>
</Section>


<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Section Label="sect:Acknowledgments">
<Heading>Acknowledgments</Heading>

The perl script<Index Key="perl"><F>perl</F></Index>
that had been used for fetching remote data until version&nbsp;1.2
had been kindly provided by Frank Lübeck and Max Neunhöffer.
Thanks also to Greg Gamble and Alexander Hulpke for technical hints
concerning <Q>standard</Q> perl.

<P/>

Ulrich Kaiser helped with preparing the package for MS Windows.

<P/>

The idea to support private extensions of the package
(see Chapter&nbsp;<Ref Chap="chap:Private Extensions"/>)
is due to Klaus Lux.
He used a preliminary version of <Package>AtlasRep</Package> Version&nbsp;1.1,
and helped to fix several bugs.

<P/>

The functions <Ref Func="CMtxBinaryFFMatOrPerm"/> and
<Ref Func="FFMatOrPermCMtxBinary"/> were contributed by Frank Lübeck.

<P/>

The &GAPDoc; package <Cite Key="GAPDoc"/>,
which is used for processing the manual of the <Package>AtlasRep</Package>
package and for processing the bibliographies included in this package
(see <Ref Func="BrowseBibliographySporadicSimple"/>),
was written by Frank Lübeck and Max Neunhöffer.

<P/>

The &GAP; package <Package>IO</Package> <Cite Key="IO"/>,
which is recommended for transferring data,
was written by Max Neunhöffer.

<P/>

Max has also suggested the generalization of the data access described in
Section&nbsp;<Ref Subsect="subsect:Customizing the Access to Data files"/>,
and the admissibility of the function
<Ref Func="Character" Label="for a character table and a list" BookName="ref"/>
as a filter in <Ref Func="DisplayAtlasInfo"/>,
<Ref Func="OneAtlasGeneratingSetInfo"/>, and
<Ref Func="AllAtlasGeneratingSetInfos"/>.

<P/>

Gunter Malle suggested to make the information about representations
of minimal degree accessible,
see Section&nbsp;<Ref Sect="sect:Representations of Minimal Degree"/>.

<P/>

Andries Brouwer suggested to add a tutorial,
see Chapter <Ref Chap="chap:tutorial"/>.
Klaus Lux suggested several improvements of this new chapter.

</Section>


<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->

</Chapter>

