= p_group_cohomology-2.0 = == Description == Modular Cohomology Rings of Finite Groups The documentation of the package is provided at http://sage.math.washington.edu/home/SimonKing/Cohomology/ == License == Copyright (C) 2010 Simon A. King Copyright (C) 2009 Simon A. King and David J. Green Distributed under the terms of the GNU General Public License (GPL), version 2 or later (at your choice). This code is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. The full text of the GPL is available at: http://www.gnu.org/licenses/ The package includes a data base of cohomology rings of the groups of order 64 and provides access to a data base of cohomology rings of the groups of order 128 and 243, located at http://sage.math.washington.edu/home/SimonKing/Cohomology/db/ These data bases are distributed under the Creative Commons Attribution-Share Alike 3.0 License. The full text of this licence is available at http://creativecommons.org/licenses/by-sa/3.0/ == SPKG Maintainers == Simon A. King == Upstream Contact == Simon A. King David J. Green == Acknowledgements == The development of the initial version of this SPKG was funded by the German Science Foundation, DFG project GR 1585/4.1, and was accomplished at the Friedrich Schiller University Jena. Since version 1.0.1, the further work on this SPKG is funded by Marie Curie grant MTKD-CT-2006-042685 and is pursued at the National University of Ireland, Galway. We thank William Stein for giving us access to various computers on which we could build test the SPKG and on which some huge computations could be completed, and acknowledge the support by National Science Foundation Grant No. DMS-0821725. We thank Mathieu Dutour Sikitic for hints on how to use GAP more efficiently. We owe Peter Symonds the idea of using the Poincare series in a rather efficient completeness criterion. == Dependencies == - The SmallGroups library needs to be installed in GAP. - For p-groups with a prime p>2, we require Singular at least in version 3-1-0. == Special Update/Build Instructions == The package is very likely to not build or at least to not work properly on Motorola processors (because of endianness). Note that most of the code is original. Therefore we included the files from src into the Mercurial repository. The package includes a modified version of the Aachen C-MeatAxe. Since the changes are major, we included the modified sources into the Mercurial repository. A MeatAxe version that comes closest to what we started with is provided in the folder mtxoriginal, that is not under revision control. == Testing == Our package does not provide a separate test suite for the MeatAxe C-library or David Green's routines for the computation of minimal projective resolutions. But it is of course equipped with extensive doc tests in the Cython code. Note that internet access is required for these tests, as it is attempted to download cohomology rings from a public data base in the web. The script ``spkg-check`` walks through all public methods of all classes in all modules of our package and perform the respective doc test. Note that spkg-check is executed right after installation of the package, if the environment variable SAGE_CHECK is yes (do "export SAGE_CHECK=yes" on the command line before installation). Should a test fail, details are displayed on screen and can also be find in SAGEROOT/install.log. == Changelog == * 2.0 (Simon King, April 2010): The package can now compute modular cohomology rings for *any* finite groups (not just for p-groups). This is implemented in a new module pGroupCohomology.modular_cohomology, that builds on top of the old pGroupCohomology.cohomology module. While developing this extension, many rough edges of the old code have been smoothened as well. The build process now uses environment variables such as $MAKE or $MKDIR, in order to increase portability. * 1.2.p0 (Dima Pasechnik and Simon King, March 2010): Adding .hgignore (ignoring src/db and mtxoriginal). Adding a robuster test for the existence of the SmallGroups library. * 1.2 (Simon King, October 2009): Modified printing for cocycles, minor bug fixes and code improvements. The data base at sage.math has moved. New: Persistent Group Cohomology (bar codes), based on ideas of Graham Ellis and Simon King. * 1.1 (Simon King August 2009): Yoneda cocomplex, Restricted Massey powers and general Massey products. * 1.0.2 (Simon King, July 2009): Fixing a computation time regression and two minor bugs. Changing Simon King's email address * 1.0.1 (Simon King, July 2009): Licensing GPL 2 or later * 1.0 (Simon King and David Green July 2009): First public version