WIP: meataxe: extend invariant form detection

TODO: complete it, add tests
gap-system · Sep 26, 2024 · 8cb1588 · 8cb1588
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Showing 3 changed files with 13 additions and 21 deletions.
diff --git a/doc/ref/meataxe.xml b/doc/ref/meataxe.xml
@@ -572,9 +572,6 @@ on all composition factors except number <A>nr</A>.
 <Section Label="meataxe:Invariant Forms">
 <Heading>MeatAxe Functionality for Invariant Forms</Heading>
 
-The functions in this section can only be applied to an absolutely irreducible
-MeatAxe module.
-
 <ManSection>
 <Func Name="MTX.InvariantBilinearForm" Arg='module'/>
 
@@ -607,6 +604,7 @@ or <K>fail</K> if no such form exists.
 returns a basis of the underlying vector space of <A>module</A> which is contained
 in an orbit of the action of the generators of module on that space.
 This is used by <Ref Func="MTX.InvariantQuadraticForm"/> in characteristic 2.
+Requires <A>module</A> to be irreducible.
 </Description>
 </ManSection>
 

diff --git a/lib/meataxe.gi b/lib/meataxe.gi
@@ -3286,21 +3286,19 @@ end;
 ##
 #F  InvariantBilinearForm( module ) . . . .
 ##
-## Look for an invariant bilinear form of the absolutely irreducible
-## GModule module. Return fail, or the matrix of the form.
+## Look for an invariant bilinear form of the GModule module.
+## Return fail, or the matrix of the form.
 SMTX.InvariantBilinearForm:=function( module  )
    local DM, iso;
 
-   if not SMTX.IsMTXModule(module) or
-                            not SMTX.IsAbsolutelyIrreducible(module) then
-      Error(
- "Argument of InvariantBilinearForm is not an absolutely irreducible module");
+   if not SMTX.IsMTXModule(module) then
+      Error("Argument of InvariantBilinearForm is not a module");
    fi;
    if IsBound(module.InvariantBilinearForm) then
      return module.InvariantBilinearForm;
    fi;
    DM:=SMTX.DualModule(module);
-   iso:=MTX.IsomorphismIrred(module,DM);
+   iso:=MTX.IsomorphismModules(module,DM);
    if iso = fail then
        SMTX.SetInvariantBilinearForm(module, fail);
        return fail;
@@ -3343,23 +3341,19 @@ end;
 ##
 #F  InvariantSesquilinearForm( module ) . . . .
 ##
-## Look for an invariant sesquililinear form of the absolutely irreducible
-## GModule module. Return fail, or the matrix of the form.
+## Look for an invariant sesquililinear form of the GModule module.
+## Return fail, or the matrix of the form.
 SMTX.InvariantSesquilinearForm:=function( module  )
    local DM, q, r, iso, isot, l;
 
-   if not SMTX.IsMTXModule(module) or
-                            not SMTX.IsAbsolutelyIrreducible(module) then
-      Error(
- "Argument of InvariantSesquilinearForm is not an absolutely irreducible module"
-   );
+   if not SMTX.IsMTXModule(module) then
+      Error("Argument of InvariantSesquilinearForm is not a module");
    fi;
-
    if IsBound(module.InvariantSesquilinearForm) then
      return module.InvariantSesquilinearForm;
    fi;
    DM:=SMTX.TwistedDualModule(module);
-   iso:=MTX.IsomorphismIrred(module,DM);
+   iso:=MTX.IsomorphismModules(module,DM);
    if iso = fail then
        SMTX.SetInvariantSesquilinearForm(module, fail);
        return fail;

diff --git a/tst/testinstall/meataxe.tst b/tst/testinstall/meataxe.tst
@@ -234,8 +234,8 @@ gap> MTX.InvariantQuadraticForm( m );
 Error, Argument of InvariantQuadraticForm is not an absolutely irreducible mod\
 ule
 gap> MTX.OrthogonalSign( m );
-Error, Argument of InvariantBilinearForm is not an absolutely irreducible modu\
-le
+Error, Argument of InvariantQuadraticForm is not an absolutely irreducible mod\
+ule
 gap> mats:= GeneratorsOfGroup( SP( 4, 2 ) );;
 gap> m:= GModuleByMats( mats, GF(2) );;
 gap> Q:= MTX.InvariantQuadraticForm( m );