[GAP Forum] RCWA 1.5

[Stefan Kohl]

Dear Forum,

This is to announce the release of RCWA 1.5.

The RCWA package provides methods for computing in
certain infinite permutation groups acting on the integers.

Due to a change of maintainership of the GAP website it may take
some time until the new version is available at the usual location
http://www.gap-system.org/Packages/rcwa.html. In any case, you can
get RCWA 1.5 from

     http://www.cip.mathematik.uni-stuttgart.de/~kohlsn/rcwa.html .

Let me take the opportunity to point to a related recent preprint of mine:

----------------------------------------------------------------------------
Title: Three Countable Highly Transitive Simple Groups
        Containing Collatz' Permutation

Abstract: We construct three countable simple permutation groups which act
           highly transitively on N_0 resp. Z. These groups form an ascending
           chain w.r.t. inclusion. The smallest of them is generated by
           involutions which interchange two disjoint residue classes, each.
           The free group of rank 2 and the modular group PSL(2,Z) embed in
           this group. We show by means of computation that it further
           contains a certain permutation of the integers which has already
           been investigated by Lothar Collatz in 1932, and whose cycle
           structure is unknown so far.

http://www.cip.mathematik.uni-stuttgart.de/~kohlsn/preprints/simplegp.pdf
----------------------------------------------------------------------------

Wishing you fun and success using RCWA,

      Stefan Kohl