diff --git a/lib/vspchom.gi b/lib/vspchom.gi index 944dc5dec0..122267fd6d 100644 --- a/lib/vspchom.gi +++ b/lib/vspchom.gi @@ -317,8 +317,7 @@ BindGlobal( "MakeImagesInfoLinearGeneralMappingByImages", function( map ) x -> LinearCombination( B, x ) ) ); map!.corelations := Immutable( ech.relations ); map!.imagesbasispreimage := Immutable( List( ech.coeffs, - x -> LinearCombination( x, - mapi[2] ) ) ); + x -> LinearCombination( mapi[2], x ) ) ); fi; end ); diff --git a/tst/testbugfix/2021-05-11-LeftModHom.tst b/tst/testbugfix/2021-05-11-LeftModHom.tst new file mode 100644 index 0000000000..d2ee037c9a --- /dev/null +++ b/tst/testbugfix/2021-05-11-LeftModHom.tst @@ -0,0 +1,47 @@ +#4481, issue reported by Chris Wensley +gap> G := Group( (1,2,3,4,5) );; +gap> F := GF(3);; +gap> A := GroupRing( F, G );; +gap> vecA := BasisVectors( Basis( A ) );; +gap> AI := AugmentationIdeal( A );; +gap> vecI := BasisVectors( Basis( AI ) );; +gap> maps := ListWithIdenticalEntries( 5, 0 );; +gap> for j in [1..5] do +> im := List( vecI, v -> v*vecA[j] ); +> maps[j] := LeftModuleHomomorphismByImages( AI, AI, vecI, im ); +> od; +gap> M := Algebra( F, maps );; +gap> hom := LeftModuleHomomorphismByImages( A, M, vecA, maps ); +[ (Z(3)^0)*(), (Z(3)^0)*(1,2,3,4,5), (Z(3)^0)*(1,3,5,2,4), + (Z(3)^0)*(1,4,2,5,3), (Z(3)^0)*(1,5,4,3,2) ] -> +[ [ (Z(3)^0)*()+(Z(3))*(1,2,3,4,5), (Z(3)^0)*(1,2,3,4,5)+(Z(3))*(1,3,5,2,4), + (Z(3)^0)*(1,3,5,2,4)+(Z(3))*(1,4,2,5,3), + (Z(3)^0)*(1,4,2,5,3)+(Z(3))*(1,5,4,3,2) ] -> + [ (Z(3)^0)*()+(Z(3))*(1,2,3,4,5), (Z(3)^0)*(1,2,3,4,5)+(Z(3))*(1,3,5,2,4), + (Z(3)^0)*(1,3,5,2,4)+(Z(3))*(1,4,2,5,3), + (Z(3)^0)*(1,4,2,5,3)+(Z(3))*(1,5,4,3,2) ], + [ (Z(3)^0)*()+(Z(3))*(1,2,3,4,5), (Z(3)^0)*(1,2,3,4,5)+(Z(3))*(1,3,5,2,4), + (Z(3)^0)*(1,3,5,2,4)+(Z(3))*(1,4,2,5,3), + (Z(3)^0)*(1,4,2,5,3)+(Z(3))*(1,5,4,3,2) ] -> + [ (Z(3)^0)*(1,2,3,4,5)+(Z(3))*(1,3,5,2,4), + (Z(3)^0)*(1,3,5,2,4)+(Z(3))*(1,4,2,5,3), + (Z(3)^0)*(1,4,2,5,3)+(Z(3))*(1,5,4,3,2), (Z(3))*()+(Z(3)^0)*(1,5,4,3,2) + ], + [ (Z(3)^0)*()+(Z(3))*(1,2,3,4,5), (Z(3)^0)*(1,2,3,4,5)+(Z(3))*(1,3,5,2,4), + (Z(3)^0)*(1,3,5,2,4)+(Z(3))*(1,4,2,5,3), + (Z(3)^0)*(1,4,2,5,3)+(Z(3))*(1,5,4,3,2) ] -> + [ (Z(3)^0)*(1,3,5,2,4)+(Z(3))*(1,4,2,5,3), + (Z(3)^0)*(1,4,2,5,3)+(Z(3))*(1,5,4,3,2), (Z(3))*()+(Z(3)^0)*(1,5,4,3,2), + (Z(3)^0)*()+(Z(3))*(1,2,3,4,5) ], + [ (Z(3)^0)*()+(Z(3))*(1,2,3,4,5), (Z(3)^0)*(1,2,3,4,5)+(Z(3))*(1,3,5,2,4), + (Z(3)^0)*(1,3,5,2,4)+(Z(3))*(1,4,2,5,3), + (Z(3)^0)*(1,4,2,5,3)+(Z(3))*(1,5,4,3,2) ] -> + [ (Z(3)^0)*(1,4,2,5,3)+(Z(3))*(1,5,4,3,2), (Z(3))*()+(Z(3)^0)*(1,5,4,3,2), + (Z(3)^0)*()+(Z(3))*(1,2,3,4,5), (Z(3)^0)*(1,2,3,4,5)+(Z(3))*(1,3,5,2,4) + ], + [ (Z(3)^0)*()+(Z(3))*(1,2,3,4,5), (Z(3)^0)*(1,2,3,4,5)+(Z(3))*(1,3,5,2,4), + (Z(3)^0)*(1,3,5,2,4)+(Z(3))*(1,4,2,5,3), + (Z(3)^0)*(1,4,2,5,3)+(Z(3))*(1,5,4,3,2) ] -> + [ (Z(3))*()+(Z(3)^0)*(1,5,4,3,2), (Z(3)^0)*()+(Z(3))*(1,2,3,4,5), + (Z(3)^0)*(1,2,3,4,5)+(Z(3))*(1,3,5,2,4), + (Z(3)^0)*(1,3,5,2,4)+(Z(3))*(1,4,2,5,3) ] ]