Add constructive recognition of SL(2,q) in natural representation 2.0

.github/workflows/CI.yml

@@ -29,7 +29,6 @@ jobs:
           - '4.15'
           - '4.14'
           - '4.13'
-          - '4.12'
 
     steps:
       - uses: actions/checkout@v6

PackageInfo.g

@@ -266,7 +266,7 @@ PackageDoc := rec(
 ),
 
 Dependencies := rec(
-  GAP := ">=4.12",
+  GAP := ">=4.13",
   NeededOtherPackages := [
     ["AtlasRep", ">= 1.4.0"],
     ["FactInt", ">= 1.5.2"],

gap/projective/classicalnatural.gi

@@ -926,13 +926,8 @@ function(ri)
 
       # This is (P)SL2, lets set up the recognition:
       Info(InfoRecog,2,"ClassicalNatural: this is PSL_2!");
-      if IsEvenInt(q) then
-          std := RECOG.RecogniseSL2NaturalEvenChar(gm,f,false);
-          ri!.comment := "PSL2Even";
-      else
-          std := RECOG.RecogniseSL2NaturalOddCharUsingBSGS(gm,f);
-          ri!.comment := "PSL2Odd";
-      fi;
+      std := RECOG.RecogniseSL2Natural(gm,f);
+      ri!.comment := "PSL2";
       Setslptonice(ri,SLPOfElms(std.all));
       ri!.nicebas := std.bas;
       ri!.nicebasi := std.basi;

gap/projective/sl.gi

@@ -72,11 +72,7 @@ RECOG.FindStdGens_SL := function(sld)
       Info(InfoRecog,2,
            "Recognising this SL2 constructively in 2 dimensions...");
       sl2genss := GeneratorsWithMemory(sl2genss);
-      if IsEvenInt(q) then
-          resl2 := RECOG.RecogniseSL2NaturalEvenChar(Group(sl2genss),f,false);
-      else
-          resl2 := RECOG.RecogniseSL2NaturalOddCharUsingBSGS(Group(sl2genss),f);
-      fi;
+      resl2 := RECOG.RecogniseSL2Natural(Group(sl2genss),f);
       slpsl2std := SLPOfElms(resl2.all);
       bas := resl2.bas * bas;
       # We need the actual transvections: