Backports for stable-4.12

INSTALL.md

@@ -14,7 +14,6 @@ GAP INSTALLATION INSTRUCTIONS
 11. Known Problems of the Configure Process
 12. Optimisation and Compiler Options
 13. GAP for macOS
-14. Expert Windows Installation
 
 These are the installation instructions for the GAP source distribution
 on Unix (which covers Linux and macOS), and for the GAP binary distribution
@@ -702,28 +701,3 @@ For further information on how to use GNU readline, refer to section 5 above.
 
 Now simply follow the Unix installation instructions to compile and start
 GAP and then it will run in this Terminal window.
-
-
-14 Expert Windows Installation
-==============================
-
-If you need to install GAP in a non-standard directory under Windows, we advise
-to use the Windows `.exe` installers which will adjust all paths in batch files
-during the installation. Whenever you use a Windows installer or install GAP
-from a source archive, you should avoid paths with spaces, e.g. do not use
-`C:\My Programs\gap-4.X.Y`. If you need to install GAP on another logical drive,
-say `E:`, the easiest way would be just to use `E:\gap-4.X.Y`.
-
-If you need to edit a `*.bat` file to specify the path to your GAP installation
-manually, you will have to replace substrings `/c/gap-4.X.Y/` by the actual path
-to the GAP root directory in the Unix format, and substrings `C:\gap-4.X.Y\` by
-the actual path to the GAP root directory in the Windows format. Please avoid
-introducing new line breaks when editing (i.e. do not use a text editor which
-automatically wraps long lines).
-
-Please contact <support@gap-system.org> if you need further information.
-
-
-Wishing you fun and success using GAP,
-
-The GAP Group

dev/gaptest.expect

@@ -40,5 +40,16 @@ expect "data1  data2"
 send -- "1);\r"
 expect "true"
 
+# test tab completion for a non-record component object
+expect "gap> "
+send -- "g:=SmallGroup(6,1);;\r"
+expect "gap> "
+send -- "g.\t"
+send -- "1;;\r"
+expect "gap> "
+send -- "g!.S\t"
+expect "ize"
+send -- ";;\r"
+expect "gap> "
 
 exit

doc/ref/mloop.xml

@@ -1296,8 +1296,7 @@ and read in the edited file automatically.
 <Index Key="vim"><C>vim</C></Index>
 <Index Key="emacs"><C>emacs</C></Index>
 In the <F>etc</F> subdirectory of the &GAP; installation
-we provide some setup files for the editors <C>vim</C> and
-<C>emacs</C>/<C>xemacs</C>.
+we provide some setup files for the editor <C>vim</C>.
 <P/>
 <C>vim</C> is a powerful editor that understands the basic <C>vi</C> commands
 but provides much more functionality. You can find more information about it
@@ -1335,8 +1334,10 @@ augroup END
 See the headers  of the two mentioned files for  additional comments and
 adjust details according to  your personal taste.
 Send comments  and suggestions to <Email>support@gap-system.org</Email>.
-Setup files for <C>emacs</C>/<C>xemacs</C> are contained in the
-<F>etc/emacs</F> subdirectory.
+<P/>
+Users of <C>emacs</C>/<C>xemacs</C> may wish to take a look at the
+<URL Text="major-mode for editing GAP files">https://melpa.org/#/gap-mode</URL>
+by Ivan Andrus.
 
 </Section>
 

lib/cmdledit.g

@@ -990,8 +990,10 @@ GAPInfo.CommandLineEditFunctions.Functions.Completion := function(l)
     # the first two <TAB> hits try existing component names only first
     if cf.tabbang then
       searchlist := ShallowCopy(NamesOfComponents(cf.tabrec));
-    else
+    elif IsRecord(cf.tabrec) then
       searchlist := ShallowCopy(RecNames(cf.tabrec));
+    else
+      searchlist := [];
     fi;
     if cf.tabcount > 2 then
       Append(searchlist, ALL_RNAMES());

lib/grp.gi

@@ -112,16 +112,16 @@ InstallMethod(MinimalGeneratingSet,"test solvable and 2-generator noncyclic",
 function(G)
 local i;
   if not HasIsSolvableGroup(G) and IsSolvableGroup(G) and
-  CanEasilyComputePcgs(G)  then
+     CanEasilyComputePcgs(G) then
     # discovered solvable -- redo
     return MinimalGeneratingSet(G);
   elif not IsSolvableGroup(G) then
     if IsGroup(G) and (not IsCyclic(G)) and HasGeneratorsOfGroup(G)
         and Length(GeneratorsOfGroup(G)) = 2 then
       return GeneratorsOfGroup(G);
     fi;
-    TryNextMethod();
   fi;
+  TryNextMethod();
 end);
 
 #############################################################################

lib/grplatt.gi

@@ -845,11 +845,15 @@ InstallGlobalFunction(LatticeViaRadical,function(arg)
   makesubgroupclasses,cefastersize;
 
   #group order below which cyclic extension is usually faster
-  if IsPackageMarkedForLoading("tomlib","")=true then
+  # WORKAROUND: there is a disparity between the data format returned
+  # by CE and what this code expects. This could be resolved properly,
+  # but since most people will have tomlib loaded anyway, this doesn't
+  # seem worth the effort.
+  #if IsPackageMarkedForLoading("tomlib","")=true then
     cefastersize:=1; 
-  else
-    cefastersize:=40000; 
-  fi;
+  #else
+  #  cefastersize:=40000; 
+  #fi;
 
   makesubgroupclasses:=function(g,l)
   local i,m,c;

lib/grppcatr.gi

@@ -717,37 +717,15 @@ end);
 #F  NextStepCentralizer( <gens>, <cent>, <pcgsF>, <field> )
 ##
 NextStepCentralizer := function( gens, cent, pcgsF, field )
-    local   g,  newgens,  matlist,  notcentral,  h,  comm,  null,  j,  elm;
-  
+    local g, matlist, null;
+
     for g in gens do
         if Length( cent ) = 0 then return []; fi;
-
-        newgens := [];
-        matlist := [];
-        notcentral := [];
-        for h in cent do
-            comm := ExponentsOfPcElement( pcgsF, Comm( h, g ) ) * One(field);
-            if comm = Zero( field ) * comm  then
-                Add( newgens, h );
-            else
-                Add( notcentral, h );
-                Add( matlist, comm );
-            fi;
-        od;
-
-        if Length( matlist ) > 0  then
-
-            # get nullspace
-            null := TriangulizedNullspaceMat( matlist );
-
-            # calculate elements corresponding to null
-            for j  in [1..Length(null)]  do
-                elm := PcElementByExponentsNC( pcgsF, notcentral, null[j] );
-                Add( newgens, elm );
-            od;
-        fi;
-        cent := newgens;
+        matlist := List( cent, x -> ExponentsOfPcElement(pcgsF, Comm(x,g)));
+        null := TriangulizedNullspaceMat(matlist*One(field));
+        cent := List( null, x -> PcElementByExponentsNC(pcgsF, cent, x));
     od;
+
     return cent;
 end;
 

lib/matrix.gi

@@ -4052,7 +4052,7 @@ InstallGlobalFunction( DirectSumMat, function (arg)
           if IsSubset(c,F) then
             F:=c;
           else
-            Error("build field/ring");
+            F:=Field(Concatenation(GeneratorsOfField(F),GeneratorsOfField(c)));
           fi;
         fi;
       od;

lib/morpheus.gi

@@ -1746,8 +1746,11 @@ InstallGlobalFunction(Morphium,function(G,H,DoAuto)
 local len,combi,Gr,Gcl,Ggc,Hr,Hcl,bg,bpri,x,dat,
       gens,i,c,hom,free,elms,price,result,rels,inns,bcl,vsu;
 
-  IsSolvableGroup(G); # force knowledge
-  gens:=SmallGeneratingSet(G);
+  if IsSolvableGroup(G) then
+    gens:=MinimalGeneratingSet(G);
+  else
+    gens:=SmallGeneratingSet(G);
+  fi;
   len:=Length(gens);
   Gr:=MorRatClasses(G);
   Gcl:=MorMaxFusClasses(Gr);

lib/teaching.g

@@ -197,9 +197,9 @@ DeclareGlobalFunction("CosetDecomposition");
 ##  <A>H</A>-conjugacy.
 ##  <Example><![CDATA[
 ##  gap> AllHomomorphismClasses(SymmetricGroup(4),SymmetricGroup(3)); 
-##  [ [ (1,3,4,2), (1,3,4) ] -> [ (), () ],
-##    [ (1,3,4,2), (1,3,4) ] -> [ (1,2), () ],
-##    [ (1,3,4,2), (1,3,4) ] -> [ (2,3), (1,2,3) ] ]
+##  [ [ (2,4,3), (1,4,2,3) ] -> [ (), () ],
+##    [ (2,4,3), (1,4,2,3) ] -> [ (), (1,2) ],
+##    [ (2,4,3), (1,4,2,3) ] -> [ (1,2,3), (1,2) ] ]
 ##  ]]></Example>
 ##  </Description>
 ##  </ManSection>
@@ -227,16 +227,16 @@ DeclareGlobalFunction("AllHomomorphismClasses");
 ##  <Ref Func="AllAutomorphisms"/> returns all bijective endomorphisms.
 ##  <Example><![CDATA[
 ##  gap> AllHomomorphisms(SymmetricGroup(3),SymmetricGroup(3));
-##  [ [ (1,2,3), (1,2) ] -> [ (), () ], 
-##    [ (1,2,3), (1,2) ] -> [ (), (1,2) ], 
-##    [ (1,2,3), (1,2) ] -> [ (), (2,3) ], 
-##    [ (1,2,3), (1,2) ] -> [ (), (1,3) ], 
-##    [ (1,2,3), (1,2) ] -> [ (1,2,3), (1,2) ], 
-##    [ (1,2,3), (1,2) ] -> [ (1,2,3), (2,3) ], 
-##    [ (1,2,3), (1,2) ] -> [ (1,3,2), (1,2) ], 
-##    [ (1,2,3), (1,2) ] -> [ (1,2,3), (1,3) ], 
-##    [ (1,2,3), (1,2) ] -> [ (1,3,2), (1,3) ], 
-##    [ (1,2,3), (1,2) ] -> [ (1,3,2), (2,3) ] ]
+##  [ [ (2,3), (1,2,3) ] -> [ (), () ],
+##    [ (2,3), (1,2,3) ] -> [ (1,2), () ],
+##    [ (2,3), (1,2,3) ] -> [ (2,3), () ],
+##    [ (2,3), (1,2,3) ] -> [ (1,3), () ],
+##    [ (2,3), (1,2,3) ] -> [ (2,3), (1,2,3) ],
+##    [ (2,3), (1,2,3) ] -> [ (1,3), (1,2,3) ],
+##    [ (2,3), (1,2,3) ] -> [ (1,3), (1,3,2) ],
+##    [ (2,3), (1,2,3) ] -> [ (1,2), (1,2,3) ],
+##    [ (2,3), (1,2,3) ] -> [ (2,3), (1,3,2) ],
+##    [ (2,3), (1,2,3) ] -> [ (1,2), (1,3,2) ] ]
 ##  ]]></Example>
 ##  </Description>
 ##  </ManSection>
@@ -954,7 +954,11 @@ local cl,cnt,bg,bw,bo,bi,k,gens,go,imgs,params,emb,clg,sg,vsu,c,i;
     repeat
       if cnt=0 then
 	# first the small gen syst.
-	gens:=SmallGeneratingSet(H);
+        if IsSolvableGroup(H) then
+          gens:=MinimalGeneratingSet(H);
+        else
+          gens:=SmallGeneratingSet(H);
+        fi;
 	sg:=Length(gens);
       else
 	# then something random

tst/testbugfix/2022-09-06-ConjugacyClassesSubgroups.tst

@@ -0,0 +1,5 @@
+# The following used to work in GAP 4.10, but was broken in GAP
+# 4.11.x and also 4.12.0.
+# See https://github.com/gap-system/gap/issues/4854
+gap> Length(ConjugacyClassesSubgroups(SmallGroup(1344,11293)));
+83

tst/testbugfix/2022-09-07-Centre.tst

@@ -0,0 +1,6 @@
+# Centre for PcGroups sometimes returned wrong results.
+# See https://github.com/gap-system/gap/issues/3940
+#
+gap> G:=SmallGroup(2^9,261648);;
+gap> Size(Center(G)); # This used to return 4
+8

tst/testbugfix/2022-09-09-MinimalGeneratingSet.tst

@@ -0,0 +1,5 @@
+gap> G:=Group((1,2),(2,3),(3,4));;
+gap> H:=Image(IsomorphismFpGroup(G));;
+gap> MinimalGeneratingSet(H);
+Error, no method found! For debugging hints type ?Recovery from NoMethodFound
+Error, no 4th choice method found for `MinimalGeneratingSet' on 1 arguments

tst/teststandard/permgrp.tst

@@ -136,5 +136,9 @@ false
 gap> IsConjugatorAutomorphism(hom);
 true
 
+# classes over larger field extension 
+gap> Length(ConjugacyClasses(PSL(2,64)));
+65
+
 #
 gap> STOP_TEST( "permgrp.tst", 1);