Does GAP3.4.4 have a function that returns the cells that define a
user-specified equivalence relation?
For illustration, suppose S and A are respectively a subset and subgroup of
the group G. Let ~ be the equivalence relation on S defined by x ~ y iff x
and y are in the same right coset of A.
Does GAP have a dedicated function that allows one to define ~ and which
returns ~'s cells?