MaximalSubgroupClassReps uses AtlasRep

if available
gap-system · Aug 13, 2023 · 315c4d8 · 315c4d8
1 parent d693b2f
commit 315c4d8
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Showing 2 changed files with 31 additions and 2 deletions.
diff --git a/lib/grplatt.gi b/lib/grplatt.gi
@@ -3123,7 +3123,7 @@ local T,t,hom,inf,nam,i;
 end);
 
 InstallGlobalFunction(TomDataMaxesAlmostSimple,function(G)
-local recog,m;
+local recog,m,p,inf,a;
   # avoid the isomorphism test falling back
   if ValueOption("cheap")=true and IsInt(ValueOption("intersize")) and
   ValueOption("intersize")<=Size(G) then
@@ -3132,6 +3132,35 @@ local recog,m;
 
   recog:=TomDataAlmostSimpleRecognition(G);
   if recog=fail then
+
+    # can we use the Atlasrep package?
+    if IsSimpleGroup(G) and IsPackageMarkedForLoading("atlasrep","")=true
+      and ValueOption(NO_PRECOMPUTED_DATA_OPTION)<>true then
+      recog:=DataAboutSimpleGroup(G);
+      inf:=CallFuncList(ValueGlobal("AtlasRepInfoRecord"),[recog.tomName]);
+      p:=CallFuncList(ValueGlobal("AtlasProgram"),[recog.tomName,1,"find"]);
+      if p<>fail and inf<>fail and IsBound(inf.nrMaxes) then
+        Info(InfoLattice,1,"Maxes of ",recog.tomName," by ATLAS words");
+        a:=CallFuncList(ValueGlobal("ResultOfBBoxProgram"),[p.program,G]);
+        p:=List([1..inf.nrMaxes],
+          x->CallFuncList(ValueGlobal("AtlasProgram"),[inf.name,1,"maxes",x]));
+        m:=List(p,x->CallFuncList(ValueGlobal("ResultOfStraightLineProgram"),
+          [x.program,a]));
+        m:=List(m,x->SubgroupNC(G,x));
+        return m;
+      elif inf<>fail and IsBound(inf.nrMaxes) then
+        Info(InfoLattice,1,"Maxes of ",recog.tomName," by ATLAS group");
+        a:=CallFuncList(ValueGlobal("AtlasGroup"),[inf.name]);
+        recog:=IsomorphismGroups(a,G);
+        m:=List([1..inf.nrMaxes],x->CallFuncList(
+          ValueGlobal("AtlasSubgroup"),[inf.name,x]));
+        if ForAny(m,x->x=fail) then return fail;fi;
+        Assert(1,ForAll(m,x->IsSubset(a,x)));
+        m:=List(m,x->Image(recog,x));
+        return m;
+      fi;
+    fi;
+
     return fail;
   fi;
   m:=List(MaximalSubgroupsTom(recog[2])[1],i->RepresentativeTom(recog[2],i));

diff --git a/tst/teststandard/permgrp.tst b/tst/teststandard/permgrp.tst
@@ -2,7 +2,7 @@
 ##
 ##  Some tests for permutation groups and friends(takes a few seconds to run)
 ##
-#@local g, dc, ac, p, s, dc1, u, part, iso,l,it,i
+#@local g, dc, ac, p, s, dc1, u, part, iso,l,it,i,w,d,a,hom
 gap> START_TEST("permgrp.tst");
 gap> Size(Normalizer(SymmetricGroup(100),PrimitiveGroup(100,1)));
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