Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Add DirectProductOfPermGroupsWithMovedPoints helper #4326

Merged
merged 2 commits into from
Mar 25, 2021
Merged

Add DirectProductOfPermGroupsWithMovedPoints helper #4326

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
05d59f1
Add DirectProductOfPermGroupsWithMovedPoints helper
fingolfin Mar 21, 2021
01676ad
Make some lists in DirectProductInfo immutable
fingolfin Mar 23, 2021
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
42 changes: 27 additions & 15 deletions lib/gprdperm.gi
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -12,21 +12,13 @@

#############################################################################
##
#M DirectProductOp( <grps>, <G> ) . . . . . . direct product of perm groups
#F DirectProductOfPermGroupsWithMovedPoints( <grps>, <pnts> )
##
InstallMethod( DirectProductOp,
"for a list of permutation groups, and a permutation group",
IsCollsElms,
[ IsList and IsPermCollColl, IsPermGroup ], 0,
function( grps, G )
local oldgrps, olds, news, perms, gens,
BindGlobal("DirectProductOfPermGroupsWithMovedPoints",
function( grps, pnts )
local i, oldgrps, olds, news, perms, gens,
deg, grp, old, new, perm, gen, D, info;

# Check the arguments.
if not ForAll( grps, IsGroup ) then
TryNextMethod();
fi;

oldgrps := [ ];
olds := [ ];
news := [ ];
Expand All @@ -35,11 +27,12 @@ InstallMethod( DirectProductOp,
deg := 0;

# loop over the groups
for grp in grps do
for i in [1..Length(grps)] do

# find old domain, new domain, and conjugating permutation
old := MovedPoints( grp );
new := [deg+1..deg+Length(old)];
grp := grps[i];
old := Immutable(pnts[i]);
new := MakeImmutable([deg+1..deg+Length(old)]);
perm := MappingPermListList( old, new );
deg := deg + Length(old);
Add( oldgrps, grp );
Expand All @@ -66,6 +59,25 @@ InstallMethod( DirectProductOp,
end );


#############################################################################
##
#M DirectProductOp( <grps>, <G> ) . . . . . . direct product of perm groups
##
InstallMethod( DirectProductOp,
"for a list of permutation groups, and a permutation group",
IsCollsElms,
[ IsList and IsPermCollColl, IsPermGroup ], 0,
function( grps, G )

# Check the arguments.
if not ForAll( grps, IsGroup ) then
TryNextMethod();
fi;

return DirectProductOfPermGroupsWithMovedPoints(grps, List(grps, MovedPoints));
end );


#############################################################################
##
#M Size( <D> ) . . . . . . . . . . . . . . . . . . . . . . of direct product
Expand Down
7 changes: 7 additions & 0 deletions tst/testinstall/gprd.tst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -45,5 +45,12 @@ gap> d4 := DirectProduct(g1, g2, g3);;
gap> HasIsFinite(d4) and not IsFinite(d4);
true

#
gap> d1 := DirectProductOfPermGroupsWithMovedPoints([g1, g1, g1], [[1..4], [1..4], [1..4]]);;
gap> MovedPoints(d1);
[ 1, 2, 3, 5, 6, 7, 9, 10, 11 ]
gap> HasIsFinite(d1) and IsFinite(d1);
true

#
gap> STOP_TEST("gprd.tst");