Attractor-Cycle Notation Fix

New parsing algorithm for the attractor-cycle notation. The previous convoluted solution did not always work for more than 9 states. Breaking change: the implementation now strictly follows the context-free grammar specification, thus the expression "[1|2,3,4]" is now treated as malformed. Adding more tests for the notation. Technical function SgpDecTestInstall2 added to get some information on memory usage of tests.

Covering Lemma & Summer Solstice

Covering Lemma implementation. Code for essential dependencies revised and corrected. Switching to Break Versioning.

Closing the 0.9-series

Better constructors for Cascades needed by the upcoming Covering Lemma implementation.
Cascades now have a partially implemented List interface. This was needed to be able use them in HashMaps. BREAKING CHANGE: as a consequence, the ^ operation is not registered any more for OnCoordinates.
Skeleton visualisation: non-image singletons visually separated to an additional level, but not contributing to depth.
Direct depth calculation - height computation removed. Some decomposition may change as the loose components are pushed upwards.
MaxChainOfEssentialDependency added.

Attractor-Cycle Notation

BREAKING CHANGES: ContainsSet(sk, P) replaced with P in ExtendedImageSet(sk), since ExtendedImageSet is now a HashSet for faster lookup.
SortedExtendedImageSet added for retaining the functionality of having a sorted list of the extended images.
CompactNotation has different semantics now and it is renamed to AttractorCycleNotation. LinearNotation has been removed.

Other changes:
DotTransformation added.
ComputeSkeletonNavigationTables added. This replaces the previous caching mechanisms. With this all skeleton navigation functions can be precomputed.

Changing representative sets

MakeRepresentative added.

Essential dependencies

Preliminary functions for finding essential dependencies added. Skeleton code partially revised and simplified.

GAP 4.12 compatibility release

Due to an upstream change in the Semigroups package older versions are not working with GAP 4.12, hence the new release.
For GAP 4.11, SgpDec v0.9.3 is the last working release.

Removing the star state

The star state was added previously to explicitly represent the situation where the cascade action 'jumps over' some levels. However, the extra states unnecessarily increase the size of the component state sets, leading to bigger decompositions. This release removes the star state and uses the constant 1 map as the default component action. Thus, the decompositions will be smaller.

v0.9.2 Usability improvements for group decompositions

Making FL conversion functions polymorphic, so they can either take an FLCascadeGroup for convenience, or a list of transversals if obtaining a decompositions (lifting the generators) is not feasible.

v0.9.1 improvements in group decomposition

Separating computation of transversals and component groups into different functions: FLTransversals, FLComponents. This is useful for computing decompositions partially, in case the whole FLCascadeGroup is not feasible. ValidPoints is now defined as an attribute of FLCascadeGroup to avoid recalculation. Standard way of testing with TestPackage("sgpdec") is available now.