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############################################################################
##
## ideals/lambda-rho.gi
## Copyright (C) 2013-2022 James D. Mitchell
##
## Licensing information can be found in the README file of this package.
##
#############################################################################
##
InstallMethod(AsList, "for an ideal orb", [IsIdealOrb],
o -> Concatenation(List(o!.orbits, AsList)));
InstallMethod(Enumerate, "for an ideal orb, and a number",
[IsIdealOrb, IsCyclotomic],
function(o, limit)
local newlookfunc;
if IsClosedOrbit(o) then
return o;
fi;
newlookfunc := {data, x} -> IsClosedOrbit(o) or Length(o) >= limit;
Enumerate(SemigroupData(o!.parent), infinity, newlookfunc);
return o;
end);
InstallMethod(Enumerate, "for an ideal orb, a number, and a function",
[IsIdealOrb, IsCyclotomic, IsFunction],
function(o, limit, lookfunc)
local newlookfunc;
newlookfunc := {data, x} -> IsClosedOrbit(o) or Length(o) >= limit;
if IsLambdaOrb(o) then
Enumerate(SemigroupData(o!.parent), infinity,
rec(lookfunc := newlookfunc, lambdalookfunc := lookfunc));
elif IsRhoOrb(o) then
Enumerate(SemigroupData(o!.parent), infinity,
rec(lookfunc := newlookfunc, rholookfunc := lookfunc));
fi;
return o;
end);
InstallMethod(Length, "for a ideal orb",
[IsIdealOrb],
o -> Sum(o!.lens));
InstallMethod(Length, "for an ideal inverse orb",
[IsIdealOrb and IsInverseOrb],
o -> Length(o!.orbit));
InstallMethod(IsBound\[\], "for an ideal orb and positive integer",
[IsIdealOrb, IsPosInt],
function(o, i)
local nr;
nr := 1;
while IsBound(o!.orbits[nr]) and i > Length(o!.orbits[nr]) do
i := i - Length(o!.orbits[nr]);
nr := nr + 1;
od;
return IsBound(o!.orbits[nr]) and IsBound(o!.orbits[nr][i]);
end);
InstallMethod(IsBound\[\], "for an inverse ideal orb and positive integer",
[IsIdealOrb and IsInverseOrb, IsPosInt],
{o, i} -> IsBound(o!.orbit[i]));
InstallMethod(ELM_LIST, "for an ideal orb and positive integer",
[IsIdealOrb, IsPosInt],
function(o, i)
local nr;
nr := 1;
while i > Length(o!.orbits[nr]) do
i := i - Length(o!.orbits[nr]);
nr := nr + 1;
od;
return o!.orbits[nr][i];
end);
InstallMethod(ELM_LIST, "for an inverse ideal orb and positive integer",
[IsIdealOrb and IsInverseOrb, IsPosInt], {o, i} -> o!.orbit[i]);
# same method for inverse ideal orbs
InstallMethod(\in, "for an object and ideal orb",
[IsObject, IsIdealOrb], {obj, o} -> HTValue(o!.ht, obj) <> fail);
# same method for inverse ideal orbs
InstallMethod(Position, "for an ideal orb, object, zero cyc",
[IsIdealOrb, IsObject, IsZeroCyc], {o, obj, n} -> HTValue(o!.ht, obj));
# same method for inverse ideal orbs
InstallMethod(OrbitGraph, "for an ideal orb",
[IsIdealOrb], o -> o!.orbitgraph);
InstallMethod(ViewObj, "for a ideal orb",
[IsIdealOrb],
function(o)
Print("<");
if IsClosedOrbit(o) then
Print("closed ");
else
Print("open ");
fi;
if IsInverseOrb(o) then
Print("inverse ");
fi;
Print("ideal ");
if IsLambdaOrb(o) then
Print("lambda ");
else
Print("rho ");
fi;
Print("orbit with ", Length(o) - 1, " points");
if not IsInverseOrb(o) then
Print(" in ", Length(o!.orbits) - 1, " components");
fi;
Print(">");
return;
end);
# different method for inverse semigroup ideals
InstallMethod(LambdaOrb, "for an acting semigroup ideal",
[IsActingSemigroup and IsSemigroupIdeal],
function(I)
local S, gens, record, htopts, fam;
S := SupersemigroupOfIdeal(I);
gens := List(GeneratorsOfSemigroup(S), x -> ConvertToInternalElement(S, x));
record := rec();
record.orbits := [[fail]];
record.lens := [1];
record.parent := I;
record.scc := [[1]];
record.scc_reps := [fail];
record.scc_lookup := [1];
record.schreiergen := [fail];
record.schreierpos := [fail];
record.orbitgraph := [[]];
record.looking := false;
record.gens := gens;
record.orbschreierpos := [];
record.orbschreiergen := [];
record.orbschreiercmp := [];
# <o!.orbits[i]> is obtained from the component
# <o!.orbits[o!.orbschreiercmp[i]]> by applying right multiplying some
# element of the ideal with lambda value in position <o!.schreierpos[i]> by
# <o!.schreiergen[i]>.
record.orbtogen := [];
# ComponentOfIndex(o, Position(o, LambdaFunc(M)(gens[orbtogen[i]])))=i
# and <orbtogen[ComponentOfIndex(Position(o, LambdaFunc(I)(gens[i])))]=i>
# i.e. component <i> arises from <gens[orbtogen[i]]>.
htopts := ShallowCopy(LambdaOrbOpts(I));
htopts.treehashsize := SEMIGROUPS.OptionsRec(I).hashlen;
record.ht := HTCreate(LambdaFunc(I)(gens[1]), htopts);
fam := CollectionsFamily(FamilyObj(LambdaFunc(I)(Representative(I))));
return Objectify(NewType(fam, IsIdealOrb and IsLambdaOrb), record);
end);
InstallMethod(RhoOrb, "for an acting semigroup ideal",
[IsActingSemigroup and IsSemigroupIdeal],
function(I)
local S, gens, record, htopts, fam;
S := SupersemigroupOfIdeal(I);
gens := List(GeneratorsOfSemigroup(S), x -> ConvertToInternalElement(S, x));
record := rec();
record.orbits := [[fail]];
record.lens := [1];
record.parent := I;
record.scc := [[1]];
record.scc_reps := [fail];
record.scc_lookup := [1];
record.schreiergen := [fail];
record.schreierpos := [fail];
record.orbitgraph := [[]];
record.looking := false;
record.gens := gens;
record.orbschreierpos := [];
record.orbschreiergen := [];
record.orbschreiercmp := [];
# <o!.orbits[i]> is obtained from the component
# <o!.orbits[o!.orbschreiercmp[i]]> by applying left multiplying some
# element of the ideal with rho value in position <o!.schreierpos[i]> by
# <o!.schreiergen[i]>.
record.orbtogen := [];
# <ComponentOfIndex(o, Position(o, RhoFunc(I)(gens[orbtogen[i]])))=i>
# and <orbtogen[ComponentOfIndex(Position(o, RhoFunc(I)(gens[i])))]=i>
# i.e. component <i> arises from <gens[orbtogen[i]]>.
htopts := ShallowCopy(RhoOrbOpts(I));
htopts.treehashsize := SEMIGROUPS.OptionsRec(I).hashlen;
record.ht := HTCreate(RhoFunc(I)(gens[1]), htopts);
fam := CollectionsFamily(FamilyObj(RhoFunc(I)(Representative(I))));
return Objectify(NewType(fam, IsIdealOrb and IsRhoOrb), record);
end);
# The entire lambda orbit of an ideal of an inverse semigroup is obtained from
# the lambda values of the generators (and their inverses) of the ideal by
# acting on the right by the generators (and their inverses) of the
# supersemigroup. Hence we require a different case here.
# Don't think that this applies to semigroups of matrices over finite fields,
# so this doesn't require us to use ConvertToInternalElement
# TODO(FixExtremeTests): check that this is really correct
InstallMethod(LambdaOrb, "for an inverse acting semigroup rep ideal",
[IsInverseActingSemigroupRep and IsSemigroupIdeal],
function(I)
local record, gens, lambdafunc, o, ht, nr, nrgens, lambda, InstallPointInOrb,
x, i;
record := ShallowCopy(LambdaOrbOpts(I));
record.scc_reps := [FakeOne(GeneratorsOfSemigroupIdeal(I))];
record.schreier := true;
record.orbitgraph := true;
record.storenumbers := true;
record.log := true;
record.parent := I;
record.treehashsize := SEMIGROUPS.OptionsRec(I).hashlen;
record.orbtogen := [];
# orbtogen[Position(o, LambdaFunc(I)(gens[i]))]=i and
gens := GeneratorsOfSemigroupIdeal(I);
lambdafunc := LambdaFunc(I);
o := Orb(GeneratorsOfSemigroup(SupersemigroupOfIdeal(I)),
LambdaOrbSeed(I),
LambdaAct(I),
record);
# install the lambda values of the generators
ht := o!.ht;
nr := 1;
nrgens := Length(gens);
lambdafunc := LambdaFunc(I);
#
InstallPointInOrb := function(lambda)
nr := nr + 1;
HTAdd(ht, lambda, nr);
Add(o!.orbit, lambda);
Add(o!.schreierpos, fail);
Add(o!.schreiergen, fail);
Add(o!.orbitgraph, []);
end;
#
for i in [1 .. nrgens] do
x := gens[i];
lambda := lambdafunc(x);
if HTValue(ht, lambda) = fail then
InstallPointInOrb(lambda);
o!.orbtogen[nr] := i;
fi;
lambda := lambdafunc(x ^ -1);
if HTValue(ht, lambda) = fail then
InstallPointInOrb(lambda);
o!.orbtogen[nr] := nrgens + i;
fi;
od;
o!.pos := 2;
# don't apply the generators of the supersemigroup of <I> to the dummy point
# at the start of the orbit (otherwise we just get the lambda orbit of the
# supersemigroup
SetFilterObj(o, IsLambdaOrb and IsInverseOrb and IsIdealOrb);
return o;
end);
# For an ideal rho orb <o>, rho value <pt> of <x>, <x> itself an element of the
# ideal, <pos> is the position in <o> of the rho value from which <x> was
# obtained by right multiplication by, the <gen>th generator of the parent of
# <o>, <ind> is the index of the generator of the ideal which we are adding (if
# applicable).
#
# This assumes that <pt> is not in <o> already, and that either:
#
# - <pos=gen=fail> and we are updating with the <ind>th generator of the
# *ideal*; or
#
# - <pos>, <gen> are positive integers and <ind=fail>
InstallGlobalFunction(UpdateIdealLambdaOrb,
function(o, pt, x, pos, gen, ind, lookfunc)
local I, record, len, S, gens, new, ht, found, nrorb, cmp, i;
I := o!.parent;
record := ShallowCopy(LambdaOrbOpts(I));
record.schreier := true;
record.orbitgraph := true;
record.storenumbers := true;
record.log := true;
record.parent := I;
record.treehashsize := SEMIGROUPS.OptionsRec(I).hashlen;
len := Length(o);
if len <> 0 then
record.gradingfunc := {new, x} -> HTValue(o!.ht, x) <> fail;
record.onlygrades := {x, data} -> not x;
record.onlygradesdata := fail;
fi;
S := SupersemigroupOfIdeal(I);
gens := List(GeneratorsOfSemigroup(S), x -> ConvertToInternalElement(S, x));
new := Orb(gens, pt, LambdaAct(I), record);
Enumerate(new);
ht := o!.ht;
if lookfunc = ReturnFalse then
for i in [1 .. Length(new)] do
HTAdd(ht, new[i], i + len);
od;
else
o!.looking := true;
o!.found := false;
found := false;
for i in [1 .. Length(new)] do
HTAdd(ht, new[i], i + len);
if not found and lookfunc(new, new[i]) then
o!.found := i;
found := true;
fi;
od;
fi;
o!.scc_reps[Length(o!.scc) + 1] := x;
Append(o!.scc_lookup, OrbSCCLookup(new) + Length(o!.scc));
Append(o!.scc, OrbSCC(new) + len);
Append(o!.schreiergen, new!.schreiergen);
Add(o!.schreierpos, fail);
for i in [2 .. Length(new)] do
Add(o!.schreierpos, new!.schreierpos[i] + len);
od;
Append(o!.orbitgraph, new!.orbitgraph + len);
Unbind(new!.scc);
Unbind(new!.trees);
Unbind(new!.scc_lookup);
Unbind(new!.mults);
Unbind(new!.schutz);
Unbind(new!.reverse);
Unbind(new!.rev);
Unbind(new!.schutzstab);
Unbind(new!.factorgroups);
Unbind(new!.factors);
Unbind(new!.orbitgraph);
Unbind(new!.schreiergen);
Unbind(new!.schreierpos);
o!.orbits[Length(o!.orbits) + 1] := new;
o!.lens[Length(o!.orbits)] := Length(new);
nrorb := Length(o!.orbits);
o!.orbschreierpos[nrorb] := pos;
o!.orbschreiergen[nrorb] := gen;
if pos <> fail then
# find the component containing <pos>
cmp := 1;
while pos > Length(o!.orbits[cmp]) do
pos := pos - Length(o!.orbits[cmp]);
cmp := cmp + 1;
od;
o!.orbschreiercmp[nrorb] := cmp;
else
o!.orbschreiercmp[nrorb] := fail;
fi;
if ind <> fail then
o!.orbtogen[nrorb] := ind;
fi;
return len + 1;
end);
# For an ideal rho orb <o>, rho value <pt> of <x>, <x> itself an element of the
# ideal, <pos> is the position in <o> of the rho value from which <x> was
# obtained by right multiplication by, the <gen>th generator of the parent of
# <o>, <ind> is the index of the generator of the ideal which we are adding (if
# applicable).
#
# This assumes that <pt> is not in <o> already, and that either:
#
# - <pos=gen=fail> and we are updating with the <ind>th generator of the
# *ideal*; or
#
# - <pos>, <gen> are positive integers and <ind=fail>
InstallGlobalFunction(UpdateIdealRhoOrb,
function(o, pt, x, pos, gen, ind, lookfunc)
local I, record, len, S, gens, new, ht, found, nrorb, cmp, i;
I := o!.parent;
record := ShallowCopy(RhoOrbOpts(I));
record.schreier := true;
record.orbitgraph := true;
record.storenumbers := true;
record.log := true;
record.parent := I;
record.treehashsize := SEMIGROUPS.OptionsRec(I).hashlen;
len := Length(o);
if len <> 0 then
record.gradingfunc := {new, x} -> HTValue(o!.ht, x) <> fail;
record.onlygrades := {x, data} -> not x;
record.onlygradesdata := fail;
fi;
S := SupersemigroupOfIdeal(I);
gens := List(GeneratorsOfSemigroup(S), x -> ConvertToInternalElement(S, x));
new := Orb(gens, pt, RhoAct(I), record);
Enumerate(new);
ht := o!.ht;
if lookfunc = ReturnFalse then
for i in [1 .. Length(new)] do
HTAdd(ht, new[i], i + len);
od;
else
o!.looking := true;
o!.found := false;
found := false;
for i in [1 .. Length(new)] do
HTAdd(ht, new[i], i + len);
if not found and lookfunc(new, new[i]) then
o!.found := i;
found := true;
fi;
od;
fi;
o!.scc_reps[Length(o!.scc) + 1] := x;
Append(o!.scc_lookup, OrbSCCLookup(new) + Length(o!.scc));
Append(o!.scc, OrbSCC(new) + len);
Append(o!.schreiergen, new!.schreiergen);
Add(o!.schreierpos, fail);
for i in [2 .. Length(new)] do
Add(o!.schreierpos, new!.schreierpos[i] + len);
od;
Append(o!.orbitgraph, new!.orbitgraph + len);
Unbind(new!.scc);
Unbind(new!.trees);
Unbind(new!.scc_lookup);
Unbind(new!.mults);
Unbind(new!.schutz);
Unbind(new!.reverse);
Unbind(new!.rev);
Unbind(new!.schutzstab);
Unbind(new!.factorgroups);
Unbind(new!.factors);
Unbind(new!.orbitgraph);
Unbind(new!.schreiergen);
Unbind(new!.schreierpos);
o!.orbits[Length(o!.orbits) + 1] := new;
o!.lens[Length(o!.orbits)] := Length(new);
nrorb := Length(o!.orbits);
o!.orbschreierpos[nrorb] := pos;
o!.orbschreiergen[nrorb] := gen;
if pos <> fail then
# find the component containing <pos>
cmp := 1;
while pos > Length(o!.orbits[cmp]) do
pos := pos - Length(o!.orbits[cmp]);
cmp := cmp + 1;
od;
o!.orbschreiercmp[nrorb] := cmp;
else
o!.orbschreiercmp[nrorb] := fail;
fi;
# jj assume that if a generator is passed into UpadateIdealRhoOrb then
# pos = the index of the generator and ind<>fail.
if ind <> fail then
o!.orbtogen[nrorb] := ind;
fi;
return len + 1;
end);
InstallMethod(EvaluateWord, "for an ideal orb and an ideal word (Semigroups)",
[IsIdealOrb, IsList], 2, # to beat the methods for lambda/rho orbs below
function(o, w)
local super_gens, I, ideal_gens, res, i;
# it is safe to use <GeneratorsOfSemigroup> here since an ideal can't be
# obtained using <ClosureSemigroup>
super_gens := o!.gens;
# = GeneratorsOfSemigroup(SupersemigroupOfIdeal(o!.parent));
I := o!.parent;
ideal_gens := List(GeneratorsOfSemigroupIdeal(I),
x -> ConvertToInternalElement(I, x));
res := ideal_gens[AbsInt(w[2])] ^ SignInt(w[2]);
for i in [1 .. Length(w[1])] do
res := super_gens[w[1][i]] * res;
od;
for i in [1 .. Length(w[3])] do
res := res * super_gens[w[3][i]];
od;
return res;
end);
InstallMethod(EvaluateWord, "for a lambda orb and a word (Semigroups)",
[IsLambdaOrb, IsList], 1,
# to beat the methods for IsXCollection
{o, w} -> EvaluateWord(o!.gens, w));
InstallMethod(EvaluateWord, "for a rho orb and a word (Semigroups)",
[IsRhoOrb, IsList], 1,
# to beat the methods for IsXCollection
{o, w} -> EvaluateWord(o!.gens, w));
# returns a triple [leftword, nr, rightword] where <leftword>, <rightword> are
# words in the generators of the supersemigroup of the ideal, and <nr> is the
# index of a generator of the ideal.
InstallMethod(TraceSchreierTreeForward,
"for an inverse semigroup ideal orbit and a positive integer",
[IsInverseOrb and IsIdealOrb, IsPosInt],
function(o, i)
local schreierpos, schreiergen, rightword, nr;
schreierpos := o!.schreierpos;
schreiergen := o!.schreiergen;
rightword := [];
while schreierpos[i] <> fail do
Add(rightword, schreiergen[i]);
i := schreierpos[i];
od;
if o!.orbtogen[i] > Length(GeneratorsOfSemigroupIdeal(o!.parent)) then
nr := -o!.orbtogen[i] + Length(GeneratorsOfSemigroupIdeal(o!.parent));
else
nr := o!.orbtogen[i];
fi;
return [[], nr, Reversed(rightword)];
end);
# returns a triple [leftword, nr, rightword] where <leftword>, <rightword> are
# words in the generators of the supersemigroup of the ideal, and <nr> is the
# index of a generator of the ideal.
InstallMethod(TraceSchreierTreeForward,
"for an ideal orbit and positive integer",
[IsIdealOrb, IsPosInt],
function(o, i)
local orbschreierpos, orbschreiergen, orbschreiercmp, schreierpos,
schreiergen, leftword, rightword, nr, j;
orbschreierpos := o!.orbschreierpos;
orbschreiergen := o!.orbschreiergen;
orbschreiercmp := o!.orbschreiercmp;
schreierpos := o!.schreierpos;
schreiergen := o!.schreiergen;
leftword := [];
rightword := [];
# find the component <nr> containing <i>
nr := 1;
j := i;
while j > Length(o!.orbits[nr]) do
j := j - Length(o!.orbits[nr]);
nr := nr + 1;
od;
# trace back to the start of the component
while schreierpos[i] <> fail do
Add(rightword, schreiergen[i]);
i := schreierpos[i];
od;
while orbschreiergen[nr] <> fail do
Add(leftword, orbschreiergen[nr]);
i := orbschreierpos[nr];
nr := orbschreiercmp[nr];
while schreierpos[i] <> fail do
Add(rightword, schreiergen[i]);
i := schreierpos[i];
od;
od;
return [Reversed(leftword), o!.orbtogen[nr], Reversed(rightword)];
end);
[ Dauer der Verarbeitung: 0.41 Sekunden
(vorverarbeitet)
]
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