[GAP Forum] Migrating from GAP 3 to GAP 4

[Hebert Pérez-Rosés]

Dear all,

I have some old programs written in GAP 3, which I would like to translate
into GAP 4. The programs work with finitely presented groups, or rather,
with words on some abstract generators. For example, I have a program that
encodes a presentation of the alternating group A_5:

a:=AbstractGenerator("a");
b:=AbstractGenerator("b");
c:=AbstractGenerator("c");

Gens:=[a,b,c];

Rels:= [[a^3, IdWord], [b^2, IdWord], [c^2, IdWord],
        [b*a*b, a^2*b*a^2], [b*a^2*b, a*b*a],
        [c*a, a^2*c], [c*b*c, b*c*b], [c*b*a*c, b*c*b*a^2],
        [c*b*a^2*c, b*c*b*a]];

Obviously, GAP 4 does not recognize the function AbstractGenerator, nor the
variable IdWord. I can solve the problem of the generators, but I still
have the problem of the identity word. Is there any equivalent of IdWord in
GAP 4? More generally, what would be the best way to translate all this
into GAP 4?

By the way, is it possible to run GAP 3 on Windows 7?

Thank you very much in advance, and best regards.

Hebert Pérez-Rosés
University of Lleida, Spain