Admit non-fields as left acting domains for free (associative or Lie) algebras, and fix the zero-dimensional case

[laurentbartholdi]

This PR fixes two problems:

gap> l := FreeLieAlgebra(Rationals,1);;
gap> Grading(l).hom_components(2); # ka-boom
Error, no method found! For debugging hints type ?Recovery from NoMethodFound
gap> a := FreeAssociativeAlgebra(Rationals,1);;
gap> Grading(a).hom_components(0); # ka-boom
Error, no method found! For debugging hints type ?Recovery from NoMethodFound

which is fixed by supplying a zero element in case there are no generators to the component; and

gap> l := FreeLieAlgebra(Integers,1);;
gap> Grading(l).hom_components(2); # ka-boom
Error, usage: VectorSpace( <F>, <gens>[, <zero>][, "basis"] ) at /usr/local/Cellar/gap/4.11.0/libexec

granted, there is now little working functionality with these left modules; but I'm working on improving this situation within a package.

[fingolfin]

There is something wrong with indentation here

[fingolfin]

Could you please also provide a test case, say in tst/testbugfix/?

[laurentbartholdi]

OK, I pushed a test file. Indentation: there was a problem with tabs vs spaces in my file.

…

On Fri, Feb 5, 2021 at 12:03 AM Max Horn ***@***.***> wrote: Could you please also provide a test case, say in tst/testbugfix/? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#4245 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AARAQUBMKY7RZBTLCNWH2KTS5MRT3ANCNFSM4XDQLIDQ> .

-- Laurent Bartholdi laurent.bartholdi<at>gmail<dot>com Mathematisches Institut, Georg-August Universität zu Göttingen Bunsenstrasse 3-5, D-37073 Göttingen, Germany

[fingolfin]

Thank you