|
############################################################################
##
## elements/trans.gi
## Copyright (C) 2015-2022 James D. Mitchell
##
## Licensing information can be found in the README file of this package.
##
#############################################################################
InstallMethod(CanonicalTransformation, "for a transformation",
[IsTransformation], f -> CanonicalTransformation(f, DegreeOfTransformation(f)));
InstallMethod(CanonicalTransformation, "for a transformation",
[IsTransformation, IsInt],
function(f, n)
local digraph;
if n < DegreeOfTransformation(f) then
ErrorNoReturn("the second argument (an integer) must be at least ",
"the degree of the first argument (a transformation)");
fi;
digraph := AsDigraph(f, n);
return AsTransformation(OnDigraphs(digraph,
BlissCanonicalLabelling(digraph)));
end);
InstallMethod(TransformationByImageAndKernel, "for an image and partition",
[IsHomogeneousList, IsCyclotomicCollColl],
function(im, ker)
local flat, i;
if not ForAll(ker, class -> ForAll(class, IsPosInt)) then
ErrorNoReturn("the argument must be a list of lists of pos ints");
fi;
flat := Union(ker);
if flat <> [1 .. Length(flat)] then
ErrorNoReturn("the union of the second argument (a partition) must ",
"be [1 .. ", Length(flat), "]");
fi;
for i in [1 .. Length(ker)] do
flat{ker[i]} := [1 .. Length(ker[i])] * 0 + i;
od;
return TransformationByImageAndKernel(im, flat);
end);
InstallMethod(IndexPeriodOfSemigroupElement, "for a transformation",
[IsTransformation], IndexPeriodOfTransformation);
[ Dauer der Verarbeitung: 0.31 Sekunden
(vorverarbeitet)
]
|
