Merge pull request #648 from hulpke/fixes

More than 3 minor corrections that should make the 4.8.3 release

lib/clas.gi

@@ -421,7 +421,7 @@ end);
 
 
 InstallMethod( ConjugacyClasses, "for groups: try random search",
-  [ IsGroup ],
+  [ IsGroup and IsFinite ],
 function(G)
 local cl;
   cl:=ConjugacyClassesForSmallGroup(G);
@@ -433,7 +433,7 @@ local cl;
 end);
 
 InstallMethod( ConjugacyClasses, "try solvable method",
-    [ IsGroup ],
+    [ IsGroup and IsFinite ],
     function( G )
     local   cls,  cl,  c;
 

lib/ctbl.gi

@@ -1071,6 +1071,7 @@ InstallMethod( OrdinaryCharacterTable,
     # Store the attribute values of the interface.
     SetUnderlyingGroup( tbl, G );
     SetUnderlyingCharacteristic( tbl, 0 );
+    IsFinite(G);
     ccl:= ConjugacyClasses( G );
     idpos:= First( [ 1 .. Length( ccl ) ],
                    i -> Order( Representative( ccl[i] ) ) = 1 );

lib/gpfpiso.gi

@@ -561,10 +561,15 @@ local fpq, qgens, qreps, fpqg, rels, pcgs, p, f, qimg, idx, nimg, decomp,
     Add(rels,MappedWord(i,fpqg,qimg)/decomp(MappedWord(i,fpqg,qreps)));
   od;
   fp:=f/rels;
+  if HasGeneratorsOfGroup(N) then 
+    di:=GeneratorsOfGroup(N);
+  else
+    di:=[];
+  fi;
   hom2:=GroupHomomorphismByImagesNC(G,fp,
-	 Concatenation(Concatenation(qreps,pcgs),GeneratorsOfGroup(N)),
+	 Concatenation(Concatenation(qreps,pcgs),di),
 	 Concatenation(GeneratorsOfGroup(fp),
-	 List(GeneratorsOfGroup(N),x->One(fp))):noassert);
+	 List(di,x->One(fp))):noassert);
 
   # build decompositioninfo
   di:=rec(gens:=Concatenation(qreps,pcgs),fp:=fp,source:=G);

lib/grpmat.gi

@@ -447,8 +447,12 @@ local field, dict, acts, start, j, zerov, zero, dim, base, partbas, heads,
 #
 #  SetFilterObj( hom, IsActionHomomorphismByBase );
 #  RUN_IN_GGMBI:=p;
-  base:=ImmutableMatrix(field,base);
-  SetLinearActionBasis(hom,base);
+  if act=OnRight or act=OnPoints then
+    # only store for action on right. projective action needs is own call to
+    # `LinearActionBase' as this will set other needed parameters.
+    base:=ImmutableMatrix(field,base);
+    SetLinearActionBasis(hom,base);
+  fi;
 
   return hom;
 end);

lib/morpheus.gi

@@ -1587,7 +1587,7 @@ local d,id,H,iso,aut,auts,i,all,hom,field,dim,P,diag,mats,gens,gal;
     if Size(gal)>1 then
       # Galois
       auts:=Concatenation(auts,
-	List(SmallGeneratingSet(gal),
+	List(MinimalGeneratingSet(gal),
 		s->GroupGeneralMappingByImages(G,G,gens,List(gens,x->
 		  Image(hom,
 		    List(PreImagesRepresentative(hom,x),r->List(r,y->Image(s,y))))))));

lib/oprt.gi

@@ -3255,7 +3255,7 @@ local xset,dom,D,b,t,i,r,binv,pos,kero,dets,roots,dim,f;
   if Length(roots)<=1 then
     # 1 will always be root
     kero:=[One(f)];
-  elif IsNaturalGL(Source(hom)) then
+  elif HasIsNaturalGL(Source(hom)) and IsNaturalGL(Source(hom)) then
     # the full GL clearly will contain the kernel
     kero:=roots; # to skip test
   elif not IsSubset(D,roots) then

lib/permdeco.gi

@@ -282,16 +282,15 @@ local cs,i,k,u,o,norm,T,Thom,autos,ng,a,Qhom,Q,E,Ehom,genimages,
   # the cs with N gives a cs for M/N.
   # take the first subnormal subgroup that is not  in N. This will be the
   # subgroup
-  i:=Length(cs);
   u:=fail;
   if Size(N)=1 then
-    u:=cs[Length(cs)-1];
+    u:=cs[2];
   else
-    while u=fail and i>0 do
-      if not IsSubset(N,cs[i]) then
-	u:=ClosureGroup(N,cs[i]);
-      fi;
-      i:=i-1;
+    i:=2;
+    u:=ClosureGroup(N,cs[i]);
+    while Size(u)=Size(M) do
+      i:=i+1;
+      u:=ClosureGroup(N,cs[i]);
     od;
   fi;
 
@@ -302,7 +301,7 @@ local cs,i,k,u,o,norm,T,Thom,autos,ng,a,Qhom,Q,E,Ehom,genimages,
   Info(InfoHomClass,1,"Factor: ",Index(u,N),"^",n);
   Qhom:=ActionHomomorphism(G,o,"surjective");
   Q:=Image(Qhom,G);
-  Thom:=NaturalHomomorphismByNormalSubgroup(u,N);
+  Thom:=NaturalHomomorphismByNormalSubgroup(M,u);
   T:=Image(Thom);
   if IsSubset(M,norm) then
     # nothing outer possible
@@ -350,14 +349,14 @@ local cs,i,k,u,o,norm,T,Thom,autos,ng,a,Qhom,Q,E,Ehom,genimages,
   # allow also mapping of `a' by enlarging
   gens:=GeneratorsOfGroup(G);
 
-  if AssertionLevel()>0 then
+  if AssertionLevel()>1 then
     Ehom:=GroupHomomorphismByImages(G,w,gens,genimages);
     Assert(1,fail<>Ehom);
   else
     Ehom:=GroupHomomorphismByImagesNC(G,w,gens,genimages);
   fi;
 
-  return [w,Ehom,a,Image(Thom,u),n];
+  return [w,Ehom,a,Image(Thom,M),n];
 end);
 
 #############################################################################

lib/ratfunul.gi

@@ -1526,8 +1526,13 @@ local   fam, tmp;
 
   # construct the product and check the valuation in case zero divisors
   tmp := CoefficientsOfUnivariateRationalFunction(univ);
-  return UnivariateRationalFunctionByExtRepNC(fam,coef*tmp[1], tmp[2],tmp[3],
-           IndeterminateNumberOfUnivariateRationalFunction(univ));
+  if Length(tmp[1])=0 then
+    return UnivariateRationalFunctionByExtRepNC(fam,[], tmp[2],tmp[3],
+	    IndeterminateNumberOfUnivariateRationalFunction(univ));
+  else
+    return UnivariateRationalFunctionByExtRepNC(fam,coef*tmp[1], tmp[2],tmp[3],
+	    IndeterminateNumberOfUnivariateRationalFunction(univ));
+  fi;
 end );
 
 InstallMethod( \*, "coeff * univariate", IsCoeffsElms,

lib/teaching.g

@@ -910,7 +910,7 @@ local cl,cnt,bg,bw,bo,bi,k,gens,go,imgs,params,emb,clg,sg,vsu,c,i;
     if Size(H)=1 then
       k:=One(H);
     else
-      k:=SmallGeneratingSet(H)[1];
+      k:=MinimalGeneratingSet(H)[1];
     fi;
     c:=Order(k);
     Assert(1,Order(k)=Order(H));

tst/teststandard/bugfix.tst

@@ -2988,6 +2988,30 @@ gap> G := SemidirectProduct(H, N);;
 gap> Size(Image(Embedding(G, 1)))=Size(H);
 true
 
+#2016/3/1 (AH)
+gap> g:=PSL(6,4);;
+gap> Sum(ConjugacyClasses(g),Size)=Size(g);
+true
+gap> Size(AutomorphismGroup(TransitiveGroup(12,269)));
+14400
+
+#2016/3/3 (AH, reported by DFH)
+gap> G:=Group([[[0,1,0,0,0,0,0,0,0],[1,0,0,0,0,0,0,0,0],[0,0,0,1,0,0,0,0,0],
+> [0,0,1,0,0,0,0,0,0],[0,0,0,0,0,1,0,0,0],[0,0,0,0,1,0,0,0,0],
+> [0,0,0,0,0,0,0,1,0],[0,0,0,0,0,0,1,0,0],
+> [1,1,Z(4)^2,Z(4)^2,Z(4)^2,Z(4)^2,0,0,1]],
+> [[0,0,1,0,0,0,0,0,0],[Z(4)^2,Z(4),Z(4),0,0,0,0,0,0],
+> [Z(4),Z(4)^2,Z(4),0,0,0,0,0,0],[0,0,0,0,1,0,0,0,0],
+> [Z(4),Z(4),Z(4),1,1,0,0,0,0],[0,0,0,0,0,0,1,0,0],[1,1,1,0,0,1,1,0,0],
+> [0,0,0,0,0,0,0,0,1],[Z(4),Z(4),Z(4),0,0,0,0,1,1]]]*Z(4)^0);;
+gap> pa:=ProjectiveActionHomomorphismMatrixGroup(G);;  
+gap> r:=PseudoRandom(G);;                                       
+gap> a:=PreImagesRepresentative(pa,ImagesRepresentative(pa,r));; 
+gap> Order(r/a) in [1,3];
+true
+gap> H:=Image(pa);;Size(H);
+50232960
+
 #############################################################################
 gap> STOP_TEST( "bugfix.tst", 781280000);