> < ^ Date: Tue, 18 Aug 1998 17:21:16 +0100 (BST)
> < ^ From: Goetz Pfeiffer <Goetz.Pfeiffer@NUIGalway.ie >
< ^ Subject: MONOID package.

Dear GAP Forum,

an updated version (2.4) of the share package MONOID is now available
from the WWW page


and from the GAP Share Packages page


The package now contains a function 'PartialOrderDClasses' computing
the natural partial order of the D classes of a given transformation
semigroup, and furthermore facilities to form the union, difference
and test membership for binary relations.

The role of operations and gradings for monoid actions has changed
since version 2.1: The <operation> argument (e.g. 'OnPoints') is now
mandatory for those functions that use it, the <grading> argument now
defaults to 'x -> 1' in the case of strong orbit calculations.

A bug has been fixed (in the function 'HasseDiagram') and several
typos in the manual have been corrected.

The algorithms we developed for the MONOID package together with the
theory behind them (linking transformation monoids to permutation
groups) are described in detail in the article

Computing Transformation Semigroups
(S. A. Linton, G. Pfeiffer, E. F. Robertson, N. Ruskuc)

(as announced by Edmund Robertson in a letter to this forum on Aug 2

Any comments are welcome.

Goetz Pfeiffer.
Goetz.Pfeiffer@ucg.ie                       http://schmidt.ucg.ie/~goetz/
National University of Ireland, Galway.     phone +353-91-512027 (x 3591)

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