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Fix Issue #23: DigraphMaximalCliques #37

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Merged
merged 1 commit into from
Dec 7, 2016
Merged

Fix Issue #23: DigraphMaximalCliques #37

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35 changes: 25 additions & 10 deletions gap/cliques.gi
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Original file line number Diff line number Diff line change
Expand Up @@ -723,9 +723,9 @@ function(gr, hook, user_param, limit, include, exclude, max, size, reps)
end);

InstallGlobalFunction(DIGRAPHS_BronKerbosch,
function(gr, hook, user_param, lim, inc, exc, max, size, reps, inc_var, exc_var)
local vtx, grp, invariant_inc, invariant_exc, invariant, adj, exc_inv, start,
possible, found_orbits, add, bk, num, x;
function(gr, hook, param, lim, inc, exc, max, size, reps, inc_var, exc_var)
local vtx, invariant_inc, invariant_exc, invariant, adj, exc_inv, start,
possible, isolated, grp, found_orbits, add, bk, num, x, gen;

# Arguments must be:
# gr - a digraph
Expand Down Expand Up @@ -759,7 +759,6 @@ function(gr, hook, user_param, lim, inc, exc, max, size, reps, inc_var, exc_var)

gr := MaximalSymmetricSubdigraphWithoutLoops(gr);
vtx := DigraphVertices(gr);
grp := AutomorphismGroup(gr);

invariant_inc := Length(inc_var) = 0;
invariant_exc := Length(exc_var) = 0;
Expand Down Expand Up @@ -793,6 +792,22 @@ function(gr, hook, user_param, lim, inc, exc, max, size, reps, inc_var, exc_var)
IntersectBlist(possible, adj[x]);
od;

isolated := DigraphSources(gr); # sources = sinks = isolated vertices
if reps and not IsEmpty(isolated) then
# Optimisation for when there are isolated vertices
grp := Group(());
for gen in GeneratorsOfGroup(AutomorphismGroup(gr)) do
# Discard generators which act on the isolated points
if not SmallestMovedPoint(gen) in isolated then
grp := ClosureGroup(grp, gen);
fi;
od;
SubtractBlist(possible, BlistList(vtx, isolated));
possible[isolated[1]] := true;
else
grp := AutomorphismGroup(gr);
fi;

found_orbits := [];

# Function to find the valid cliques of an orbit given an orbit rep
Expand All @@ -801,7 +816,7 @@ function(gr, hook, user_param, lim, inc, exc, max, size, reps, inc_var, exc_var)

c := ListBlist(vtx, c);
if reps then # we are only looking for orbit reps, so add the rep
hook(user_param, c);
hook(param, c);
num := num + 1;
return;
elif not ForAny(found_orbits, x -> c in x) then
Expand All @@ -814,7 +829,7 @@ function(gr, hook, user_param, lim, inc, exc, max, size, reps, inc_var, exc_var)
# are invariant so there is nothing extra to check
n := Minimum(lim - num, n);
for c in orb{[1 .. n]} do
hook(user_param, c);
hook(param, c);
od;
num := num + n;
return;
Expand All @@ -827,7 +842,7 @@ function(gr, hook, user_param, lim, inc, exc, max, size, reps, inc_var, exc_var)
i := i + 1;
c := BlistList(vtx, orb[i]);
if SizeBlist(IntersectionBlist(exc_var, c)) = 0 then
hook(user_param, orb[i]);
hook(param, orb[i]);
num := num + 1;
fi;
od;
Expand All @@ -838,7 +853,7 @@ function(gr, hook, user_param, lim, inc, exc, max, size, reps, inc_var, exc_var)
i := i + 1;
c := BlistList(vtx, orb[i]);
if IsSubsetBlist(c, inc_var) then
hook(user_param, orb[i]);
hook(param, orb[i]);
num := num + 1;
fi;
od;
Expand All @@ -851,7 +866,7 @@ function(gr, hook, user_param, lim, inc, exc, max, size, reps, inc_var, exc_var)
c := BlistList(vtx, orb[i]);
if SizeBlist(IntersectionBlist(exc_var, c)) = 0
and IsSubsetBlist(c, inc_var) then
hook(user_param, orb[i]);
hook(param, orb[i]);
num := num + 1;
fi;
od;
Expand Down Expand Up @@ -973,5 +988,5 @@ function(gr, hook, user_param, lim, inc, exc, max, size, reps, inc_var, exc_var)
num := 0;

bk(start, possible, BlistList(vtx, []), grp, Length(inc));
return user_param;
return param;
end);
18 changes: 18 additions & 0 deletions tst/standard/cliques.tst
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -503,6 +503,24 @@ gap> c := DigraphMaximalCliques(gr);;
gap> Length(c);
12815

#T# Issue #23: Digraphs with isolated vertices
gap> gr := DigraphFromSparse6String(":~?@c__EC?_F");
<digraph with 100 vertices, 6 edges>
gap> DigraphMaximalCliquesReps(gr);
[ [ 1 ], [ 2, 3, 5 ] ]
gap> DigraphMaximalCliques(gr);
[ [ 1 ], [ 4 ], [ 6 ], [ 7 ], [ 8 ], [ 9 ], [ 10 ], [ 11 ], [ 12 ], [ 13 ],
[ 14 ], [ 15 ], [ 16 ], [ 17 ], [ 18 ], [ 19 ], [ 20 ], [ 21 ], [ 22 ],
[ 23 ], [ 24 ], [ 25 ], [ 26 ], [ 27 ], [ 28 ], [ 29 ], [ 30 ], [ 31 ],
[ 32 ], [ 33 ], [ 34 ], [ 35 ], [ 36 ], [ 37 ], [ 38 ], [ 39 ], [ 40 ],
[ 41 ], [ 42 ], [ 43 ], [ 44 ], [ 45 ], [ 46 ], [ 47 ], [ 48 ], [ 49 ],
[ 50 ], [ 51 ], [ 52 ], [ 53 ], [ 54 ], [ 55 ], [ 56 ], [ 57 ], [ 58 ],
[ 59 ], [ 60 ], [ 61 ], [ 62 ], [ 63 ], [ 64 ], [ 65 ], [ 66 ], [ 67 ],
[ 68 ], [ 69 ], [ 70 ], [ 71 ], [ 72 ], [ 73 ], [ 74 ], [ 75 ], [ 76 ],
[ 77 ], [ 78 ], [ 79 ], [ 80 ], [ 81 ], [ 82 ], [ 83 ], [ 84 ], [ 85 ],
[ 86 ], [ 87 ], [ 88 ], [ 89 ], [ 90 ], [ 91 ], [ 92 ], [ 93 ], [ 94 ],
[ 95 ], [ 96 ], [ 97 ], [ 98 ], [ 99 ], [ 100 ], [ 2, 3, 5 ] ]

#T# DIGRAPHS_UnbindVariables
gap> Unbind(f);
gap> Unbind(c);
Expand Down