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Random source for additive cosets, grpnice and external orbits #2272

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Merged
fingolfin merged 3 commits into from
Mar 21, 2018
Merged

Random source for additive cosets, grpnice and external orbits #2272

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e8e9592
Random source for additive cosets
grouptheoryenthusiast Mar 20, 2018
3e49081
InstallWithRandomSource for grpnice
grouptheoryenthusiast Mar 20, 2018
334af0d
InstallWithRandomSource for ExternalOrbits
grouptheoryenthusiast Mar 20, 2018
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8 changes: 4 additions & 4 deletions lib/addcoset.gi
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Original file line number Diff line number Diff line change
Expand Up @@ -142,11 +142,11 @@ InstallMethod( IsFinite,
##
#M Random( <A> ) . . . . . . . . . . . . . . . . . . . . for additive cosets
##
InstallMethod( Random,
"for an additive coset",
InstallMethodWithRandomSource( Random,
"for a random source and an additive coset",
true,
[ IsAdditiveCoset ], 0,
A -> Representative( A ) + Random( AdditivelyActingDomain( A ) ) );
[ IsRandomSource, IsAdditiveCoset ], 0,
{rs, A} -> Representative( A ) + Random( rs, AdditivelyActingDomain( A ) ) );


#############################################################################
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2 changes: 1 addition & 1 deletion lib/coll.gi
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Expand Up @@ -267,7 +267,7 @@ end );


RedispatchOnCondition(Random,true,[IsCollection],[IsFinite],0);
RedispatchOnCondition(Random,true,[IsRandomSource,IsCollection],[IsFinite],0);
RedispatchOnCondition(Random,true,[IsRandomSource,IsCollection],[,IsFinite],0);

#############################################################################
##
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2 changes: 1 addition & 1 deletion lib/grpnice.gi
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Expand Up @@ -783,7 +783,7 @@ SubgroupMethodByNiceMonomorphism( RadicalGroup,
##
#M Random( <G> )
##
InstallMethod( Random,
InstallMethodWithRandomSource( Random,
"for a random source and a group handled by nice monomorphism",
[ IsRandomSource, IsGroup and IsHandledByNiceMonomorphism ], 0,
{rs, G} -> PreImagesRepresentative( NiceMonomorphism( G ),
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9 changes: 5 additions & 4 deletions lib/oprt.gi
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Expand Up @@ -294,15 +294,16 @@ function( xset )
return Orbit(xset,Representative(xset));
end);

InstallMethod( Random,"for external orbit: via acting domain", true,
[ IsExternalOrbit ], 0,
function( xset )
InstallMethodWithRandomSource( Random,
"for a random source and for an external orbit: via acting domain", true,
[ IsRandomSource, IsExternalOrbit ], 0,
function( rs, xset )
if HasHomeEnumerator(xset) and not IsPlistRep(HomeEnumerator(xset)) then
TryNextMethod(); # can't do orbit because the home enumerator might
# imply a different `PositionCanonical' (and thus equivalence of objects)
# method.
fi;
return FunctionAction(xset)(Representative(xset),Random(ActingDomain(xset)));
return FunctionAction(xset)(Representative(xset),Random(rs, ActingDomain(xset)));
end);

#############################################################################
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28 changes: 28 additions & 0 deletions tst/testinstall/random.tst
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Expand Up @@ -105,6 +105,34 @@ gap> randomTest(SL(3,3), Random);
gap> randomTest(GL(2,2), Random);
gap> randomTest(GL(3,3), Random);

#
# additive cosets
#
gap> randomTest(AdditiveCoset(ZmodnZ(1),Identity(ZmodnZ(1))),Random);
gap> randomTest(AdditiveCoset(Integers,2),Random);
gap> randomTest(AdditiveCoset(CF(5),-2/3*E(5)-1/2*E(5)^2+1/3*E(5)^4),Random);
gap> randomTest(AdditiveCoset(GF(17),Z(17)^9),Random);
gap> R := SmallRing(10,2);;
gap> randomTest(AdditiveCoset(R,5*R.1),Random);
gap> a:= Algebra( GF(2), [ [ [ Z(2) ] ] ] );;
gap> rm:= FreeMagmaRing( GF(2), a );;
gap> randomTest(AdditiveCoset(rm, rm.1), Random);

#
# external orbits
#
gap> g:=DihedralGroup(8);; orbs:=ExternalOrbits(g,AsList(g));;
gap> for orb in orbs do
> randomTest(orb,Random);
> od;

#
gap> g:=SymmetricGroup(4);;
gap> orbs:=ExternalOrbits(g,[1..4]);;
gap> for orb in orbs do
> randomTest(orb,Random);
> od;

#
# other stuff
#
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