Quelle IsSupportedInOrigin.g Sprache: unbekannt

elements_of_irrelevant_ideal :=
[ "x", "y" ];

IsSupportedInOrigin := function( module_presentation )
  local number_of_generators, list_of_generators, list_of_kernel_embeddings, ideal_embedding,
        ideal_matrix, Fn1, F1, S, Sy, elem, matrix, entry;

    number_of_generators := NrColumns( UnderlyingMatrix( module_presentation ) );

    if number_of_generators = 0 then

        return true;

    fi;

    list_of_generators := List( [ 1 .. number_of_generators ], i -> StandardGeneratorMorphism( module_presentation, i ) );

    list_of_kernel_embeddings := List( list_of_generators, KernelEmbedding );

    ideal_embedding :=
      PreCompose( ProjectionInFactorOfFiberProduct( list_of_kernel_embeddings, 1 ), list_of_kernel_embeddings[1] );

    SetIsMonomorphism( ideal_embedding, true );

    S := UnderlyingHomalgRing( module_presentation );

    Sy := S * "RabinowitschTrickVariable";

    ideal_matrix := UnderlyingMatrix( ideal_embedding ) * Sy;

    Fn1 := FreeLeftPresentation( NrRows( ideal_matrix ) + 1, Sy );

    F1 := FreeLeftPresentation( 1, Sy );

    for elem in elements_of_irrelevant_ideal do

        entry := HomalgMatrix( [ [ elem ] ], 1, 1, S );

        entry := entry * Sy;

        entry := entry * HomalgMatrix( [ [ "RabinowitschTrickVariable" ] ], 1, 1, Sy ) - HomalgMatrix( [ [ "1" ] ], 1, 1, Sy );

        matrix := UnionOfRows( ideal_matrix, entry );

        if not IsEpimorphism( PresentationMorphism( Fn1, matrix, F1 ) ) then

            return false;

        fi;

    od;

    return true;

end;;

SwitchGeneralizedMorphismStandard( "span" );

Quelle IsSupportedInOrigin.g Sprache: unbekannt

[ Dauer der Verarbeitung: 0.18 Sekunden (vorverarbeitet) ]