3.0.9

This version contains some minor bugfixes, and updates for compatibility GAP
4.9, IO 4.5.0, and Digraphs 0.11.0.

3.0.8

This version contains some minor bugfixes, and updates for compatibility GAP
4.9 and Orb 4.8.0.

3.0.7

This version contains some minor bugfixes, fixes some issues where some tests in the main GAP repo returned different output when Semigroups was loaded than when it was not, and updates the kernel module for version 0.5.2 of libsemigroups. The configuration option --enable-debug was added.

The following issues are resolved:

• Issue 389: the most general method for NaturalPartialOrder sometimes returned incorrect results. [Wilf A. Wilson]

• Issue 393: StructureDescription for finitely presented groups failed with an error when Semigroups was loaded. [J. D. Mitchell]

• Issue 395: GAP's test tst/testinstall/semigrp.tst failed because of a missing method for NrEquivalenceClasses for a generic semigroup congruence. [J. D. Mitchell] and [Wilf A. Wilson]

3.0.6

This version contains some minor bugfixes, improves the compatibility of Semigroups with other GAP packages, and updates the kernel module for version 0.5.0 of libsemigroups

The following issues are resolved:

• Issue 371: the identity element of some types of monoids was not added to its GeneratorsOfSemigroup. This meant that the semigroup generated by GeneratorsOfSemigroup(M) was not equal to M in some rare cases. [Wilf A. Wilson]

• Issue 377: there was a bug in the method for IsInverseSemigroup for non-acting semigroups that sometimes returned a false positive. [Wilf A. Wilson]

3.0.5

This version contains some minor tweaks and the following issue is resolved:

• Issue 352: There was a name clash with some other GAP packages using RandomMatrix and IsTorsion. [J. D. Mitchell]

3.0.4

Some minor issues are fixed in this release:

• Issue 342 DirectProduct for transformation semigroups returned the wrong answer when applied to semigroups satisfying IsMonoidAsSemigroup. [J. D. Mitchell]

Some documentation and tests were added. [Michael Torpey]

3.0.3

Some minor issues are fixed in this release:

• Issue 336 Rees (0-)matrix semigroups over non-permutation groups sometimes resulted in an error. [J. D. Mitchell]

• A method was added for IsEUnitaryInverseSemigroup for non-inverse semigroups, which previously resulted in no method found. [Chris Russell]

• Some error messages were improved in ReadGenerators and WriteGenerators. [J. D. Mitchell]

3.0.2

The following issues were resolved:

• Issue 330 InversesOfSemigroupElement some times returned an incorrect value, specifically when applied to the identity of a transformation monoid. [J. D. Mitchell]

• Issue 328 when using Linux the package compiled but failed to link pthreads and so the kernel module failed to load in GAP. [J. D. Mitchell]

There are improvements to the following:

• some missing documentation was added. [Michael Torpey]

• the subsemigroup returned by IdempotentGeneratedSubsemigroup for Rees (0-)matrix semigroup over a group has a smaller generating set than previously, and can be found more quickly. [Wilf A. Wilson]

• IsomorphismSemigroups is extended so that it can be applied to arbitrary simple, 0-simple, or monogenic semigroups. [Wilf A. Wilson]

3.0.1

This is an extremely minor release fixing some minor issues in the last
release.

3.0.0

This is a major release that dramatically expands the scope of the package. The package now features a compiled C/C++ module which interfaces with the libsemigroups C++ library to allow high-speed computations for congruences and certain categories of semigroup. There are also several new types of semigroup and a variety of new methods which can be used with them.