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Dear GAP Forum,

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

from the WWW page

http://schmidt.ucg.ie/monoid

and from the GAP Share Packages page

http://www-gap.dcs.st-and.ac.uk/~gap/Info/share.html.

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)

http://schmidt.ucg.ie/monoid/ref.html

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

1996).

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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