Update to ModulePresentationsForCAP v2025.06-01

Author: mohamed-barakat

Project.toml

@@ -5,7 +5,7 @@ authors = [
 	"Sebastian Posur <[email protected]>",
 	"Fabian Zickgraf <[email protected]>",
 ]
-version = "0.1.6"
+version = "0.1.7"
 
 [deps]
 MatricesForHomalg = "29b9b1b6-efa6-450e-8188-a5a2c25df071"

src/gap/ModulePresentationsForCAP.gi.autogen.jl

@@ -1057,7 +1057,7 @@ end );
 
 end );
 
-@InstallGlobalFunction( ADD_LIFT_AND_COLIFT_LEFT, 
+@InstallGlobalFunction( ADD_LIFT_AND_COLIFT_LEFT,
 
   function( category )
   local homalg_ring, lift_via_compiled_linear_system_func, colift_via_compiled_linear_system_func;
@@ -1088,20 +1088,11 @@ end );
     M = UnderlyingMatrix( Source( morphism_2 ) );
 
     v = NrColumns( M );
-       
+    
     s = NrColumns( P );
 
     N = UnderlyingMatrix( Range(  morphism_1 ) );
 
-    # NrColumns( N ) == 0 implies coker(N)=0 and  s == 0 implies coker(P)=0, hence morphism_1 is zero, and the zero morphism can always be lifted. 
-    if (NrColumns( N ) == 0 || s == 0)
-        return ZeroMorphism( Source( morphism_1 ), Source( morphism_2 ) ); 
-    end;
-    
-    # if NrColumns(M)=0 then M is zero, hence lift exists iff morphism_1 is zero.
-    if (NrColumns( M ) == 0 && IsZeroForMorphisms( morphism_1 ))
-        return ZeroMorphism( Source( morphism_1 ), Source( morphism_2 ) );
-    end;
     A = UnderlyingMatrix( morphism_1 );
 
     B = UnderlyingMatrix( morphism_2 );
@@ -1110,31 +1101,23 @@ end );
 
     N_tr_I = KroneckerMat( TransposedMatrix( N ), HomalgIdentityMatrix( NrColumns( P ) ,homalg_ring ) );
 
-    zero_1  = HomalgZeroMatrix( NrRows( A )*NrColumns( A ), NrRows( P )*NrRows( M ), homalg_ring );
+    zero_1  = HomalgZeroMatrix( NrRows( A ) * NrColumns( A ), NrRows( P ) * NrRows( M ), homalg_ring );
 
     mat1 = UnionOfColumns( B_tr_I, N_tr_I, zero_1 );
 
     I_P = KroneckerMat( HomalgIdentityMatrix( NrColumns( M ) ,homalg_ring ), P );
 
-    zero_2 = HomalgZeroMatrix( NrRows( P )*NrColumns( M ), NrRows( A )*NrRows( N ), homalg_ring );
+    zero_2 = HomalgZeroMatrix( NrRows( P ) * NrColumns( M ), NrRows( A ) * NrRows( N ), homalg_ring );
 
-    M_tr_I = KroneckerMat( TransposedMatrix( M ), HomalgIdentityMatrix( NrRows( P ) ,homalg_ring ) );
+    M_tr_I = KroneckerMat( TransposedMatrix( M ), HomalgIdentityMatrix( NrRows( P ), homalg_ring ) );
 
     mat2 = UnionOfColumns( I_P, zero_2, M_tr_I );
 
     mat = UnionOfRows( mat1, mat2 );
 
-    if (NrColumns( A ) <= 1)
-       
-       vec_A = A;
-       
-    else
-       
-       vec_A = UnionOfRows( List( (1):(NrColumns( A )), i-> CertainColumns( A, [ i ] ) ) );
-       
-    end;
+    vec_A = ConvertMatrixToColumn( A );
 
-    vec_zero = HomalgZeroMatrix( NrRows( P )*NrColumns( M ), 1, homalg_ring );
+    vec_zero = HomalgZeroMatrix( NrRows( P ) * NrColumns( M ), NrColumns( vec_A ), homalg_ring );
 
     vec = UnionOfRows( vec_A, vec_zero );
 
@@ -1155,11 +1138,7 @@ end );
 
     sol = CallFuncList( LeftDivide, lift_via_compiled_linear_system_func( morphism_1, morphism_2 ) );
 
-    if (v <= 1)
-        XX = CertainRows( sol, [ 1.. s ] );
-    else
-        XX = UnionOfColumns( List( (1):(v), i-> CertainRows( sol, [ (i-1)*s+1.. i*s ] ) ) );
-    end;
+    XX = ConvertColumnToMatrix( CertainRows( sol, (1):(s * v) ), s, v );
 
     return PresentationMorphism( cat, Source( morphism_1 ), XX, Source( morphism_2 ) );
 
@@ -1195,21 +1174,11 @@ end );
     M = UnderlyingMatrix( Range( morphism_1 ) );
 
     v = NrColumns( M );
-       
+    
     s = NrColumns( I );
 
     N = UnderlyingMatrix( Source( morphism_1 ) );
 
-    # NrColumns( N ) == 0 implies coker(N)=0 and  s == 0 implies coker(I)=0, hence morphism_2 is zero, and the zero morphism can always be colifted.
-    if (NrColumns( N ) == 0 || s == 0)
-        return ZeroMorphism( Range( morphism_1 ), Range( morphism_2 ) );
-    end;
-
-    # if NrColumns(M)=0 then M is zero, hence colift exists iff morphism_2 is zero.
-    if (NrColumns( M ) == 0 && IsZeroForMorphisms( morphism_2 ))
-        return ZeroMorphism( Range( morphism_1 ), Range( morphism_2 ) );
-    end;
-
     B = UnderlyingMatrix( morphism_1 );
 
     A = UnderlyingMatrix( morphism_2 );
@@ -1226,12 +1195,8 @@ end );
 
     A_over_zero = UnionOfRows( A, zero_mat );
 
-    if (NrColumns( A ) <= 1)
-        vec = A_over_zero;
-    else
-        vec = UnionOfRows( List( (1):(NrColumns( A )), i-> CertainColumns( A_over_zero, [ i ] ) ) );
-    end;
-
+    vec = ConvertMatrixToColumn( A_over_zero );
+    
     return [ mat, vec ];
 
   end;
@@ -1249,15 +1214,7 @@ end );
 
     sol = CallFuncList( LeftDivide, colift_via_compiled_linear_system_func( morphism_1, morphism_2 ) );
 
-    v = NrColumns( M );
-    
-    s = NrColumns( I );
-    
-    if (s <= 1)
-        XX = CertainRows( sol, [ 1.. v ] );
-    else
-        XX = UnionOfColumns( List( (1):(s), i-> CertainRows( sol, [ (i-1)*v+1.. i*v ] ) ) );
-    end;
+    XX = ConvertColumnToMatrix( CertainRows( sol, (1):(v * s) ), v, s );
 
     return PresentationMorphism( cat, Range( morphism_1 ), XX, Range( morphism_2 ) );
 
@@ -1272,21 +1229,21 @@ end );
 end );
 
 ##
-@InstallGlobalFunction( ADD_LIFT_AND_COLIFT_RIGHT, 
+@InstallGlobalFunction( ADD_LIFT_AND_COLIFT_RIGHT,
 
   function( category )
   local homalg_ring, lift_via_compiled_linear_system_func, colift_via_compiled_linear_system_func;
 
   homalg_ring = category.ring_for_representation_category;
 
   lift_via_compiled_linear_system_func = function( morphism_1, morphism_2 )
-    local Pt, Nt, Mt, At, Bt, B_tr_I, N_tr_I, zero_1, 
+    local Pt, Nt, Mt, At, Bt, B_tr_I, N_tr_I, zero_1,
           mat1, mat2, I_P, zero_2, M_tr_I, mat, vec_A, vec_zero, vec, v, s;
     #                 rxs
     #                P
     #                |
-    #         uxr    | mxr 
-    #        X      (A) 
+    #         uxr    | mxr
+    #        X      (A)
     #                |
     #                V
     #    uxv    mxu   mxn
@@ -1296,10 +1253,10 @@ end );
     #   We need to solve the system
     #       B*X == A mod N
     #       X*P + M*Y == 0
-    #   I.e., looking for X, Y, Z such that 
+    #   I.e., looking for X, Y, Z such that
     #       B*X + N*Y == A
     #       X*P + M*Z == 0
-    #   which is equivalent to 
+    #   which is equivalent to
     #       XX*B^t + YY*N^t == A^t
     #       P^t*XX + ZZ*M^t == 0
     #   which can be solved exactly as Lift in left presentations case.
@@ -1314,47 +1271,31 @@ end );
 
     Nt = TransposedMatrix( UnderlyingMatrix( Range(  morphism_1 ) ) );
 
-    if (NrRows( Nt ) == 0 || s == 0)
-        return ZeroMorphism( Source( morphism_1 ), Source( morphism_2 ) ); 
-    end;
-
-    if (NrRows( Mt ) == 0 && IsZeroForMorphisms( morphism_1 ))
-        return ZeroMorphism( Source( morphism_1 ), Source( morphism_2 ) );
-    end;
-
     At = TransposedMatrix( UnderlyingMatrix( morphism_1 ) );
 
     Bt = TransposedMatrix( UnderlyingMatrix( morphism_2 ) );
 
     B_tr_I = KroneckerMat( TransposedMatrix( Bt ), HomalgIdentityMatrix( NrColumns( Pt ), homalg_ring ) );
 
-    N_tr_I = KroneckerMat( TransposedMatrix( Nt ), HomalgIdentityMatrix( NrColumns( Pt ) ,homalg_ring ) );
+    N_tr_I = KroneckerMat( TransposedMatrix( Nt ), HomalgIdentityMatrix( NrColumns( Pt ), homalg_ring ) );
 
-    zero_1  = HomalgZeroMatrix( NrRows( At )*NrColumns( At ), NrRows( Pt )*NrRows( Mt ), homalg_ring );
+    zero_1  = HomalgZeroMatrix( NrRows( At ) * NrColumns( At ), NrRows( Pt ) * NrRows( Mt ), homalg_ring );
 
     mat1 = UnionOfColumns( B_tr_I, N_tr_I, zero_1 );
 
-    I_P = KroneckerMat( HomalgIdentityMatrix( NrColumns( Mt ) ,homalg_ring ), Pt );
+    I_P = KroneckerMat( HomalgIdentityMatrix( NrColumns( Mt ), homalg_ring ), Pt );
 
-    zero_2 = HomalgZeroMatrix( NrRows( Pt )*NrColumns( Mt ), NrRows( At )*NrRows( Nt ), homalg_ring );
+    zero_2 = HomalgZeroMatrix( NrRows( Pt ) * NrColumns( Mt ), NrRows( At ) * NrRows( Nt ), homalg_ring );
 
-    M_tr_I = KroneckerMat( TransposedMatrix( Mt ), HomalgIdentityMatrix( NrRows( Pt ) ,homalg_ring ) );
+    M_tr_I = KroneckerMat( TransposedMatrix( Mt ), HomalgIdentityMatrix( NrRows( Pt ), homalg_ring ) );
 
     mat2 = UnionOfColumns( I_P, zero_2, M_tr_I );
 
     mat = UnionOfRows( mat1, mat2 );
 
-    if (NrColumns( At ) <= 1)
-       
-       vec_A = At;
-       
-    else
-       
-       vec_A = UnionOfRows( List( (1):(NrColumns( At )), i-> CertainColumns( At, [ i ] ) ) );
-       
-    end;
+    vec_A = ConvertMatrixToColumn( At );
 
-    vec_zero = HomalgZeroMatrix( NrRows( Pt )*NrColumns( Mt ), 1, homalg_ring );
+    vec_zero = HomalgZeroMatrix( NrRows( Pt ) * NrColumns( Mt ), NrColumns( vec_A ), homalg_ring );
 
     vec = UnionOfRows( vec_A, vec_zero );
 
@@ -1363,7 +1304,7 @@ end );
   end;
 
   AddLift( category, function( cat, morphism_1, morphism_2 )
-    local Pt, Mt, v, s, sol, XX;
+    local Pt, Mt, v, s, sol, XX_tr;
 
     Pt = TransposedMatrix( UnderlyingMatrix( Source( morphism_1 ) ) );
     Mt = TransposedMatrix( UnderlyingMatrix( Source( morphism_2 ) ) );
@@ -1374,13 +1315,9 @@ end );
 
     sol = CallFuncList( LeftDivide, lift_via_compiled_linear_system_func( morphism_1, morphism_2 ) );
 
-    if (v <= 1)
-        XX = TransposedMatrix( CertainRows( sol, [ 1.. s ] ) );
-    else
-        XX = TransposedMatrix( UnionOfColumns( List( (1):(v), i-> CertainRows( sol, [ (i-1)*s+1.. i*s ] ) ) ) );
-    end;
+    XX_tr = ConvertColumnToMatrix( CertainRows( sol, (1):(s * v) ), s, v );
 
-    return PresentationMorphism( cat, Source( morphism_1 ), XX, Source( morphism_2 ) );
+    return PresentationMorphism( cat, Source( morphism_1 ), TransposedMatrix( XX_tr ), Source( morphism_2 ) );
 
   end );
 
@@ -1398,19 +1335,11 @@ end );
     Mt = TransposedMatrix( UnderlyingMatrix( Range( morphism_1 ) ) );
 
     v = NrColumns( Mt );
-       
+    
     s = NrColumns( It );
-        
-    Nt = TransposedMatrix( UnderlyingMatrix( Source( morphism_1 ) ) );
 
-    if (NrRows( Nt ) == 0 || s == 0)
-        return ZeroMorphism( Range( morphism_1 ), Range( morphism_2 ) );
-    end;
+    Nt = TransposedMatrix( UnderlyingMatrix( Source( morphism_1 ) ) );
 
-    if (NrRows( Mt ) == 0 && IsZeroForMorphisms( morphism_2 ))
-        return ZeroMorphism( Range( morphism_1 ), Range( morphism_2 ) );
-    end;
-
     Bt = TransposedMatrix( UnderlyingMatrix( morphism_1 ) );
 
     At = TransposedMatrix( UnderlyingMatrix( morphism_2 ) );
@@ -1427,18 +1356,14 @@ end );
 
     A_over_zero = UnionOfRows( At, zero_mat );
 
-    if (NrColumns( At ) <= 1)
-        vec = A_over_zero;
-    else
-        vec = UnionOfRows( List( (1):(NrColumns( At )), i-> CertainColumns( A_over_zero, [ i ] ) ) );
-    end;
-
+    vec = ConvertMatrixToColumn( A_over_zero );
+    
     return [ mat, vec ];
 
   end;
 
   AddColift( category, function( cat, morphism_1, morphism_2 )
-    local It, Mt, v, s, sol, XX;
+    local It, Mt, v, s, sol, XX_tr;
 
     It = TransposedMatrix( UnderlyingMatrix( Range( morphism_2 ) ) );
 
@@ -1450,17 +1375,9 @@ end );
 
     sol = CallFuncList( LeftDivide, colift_via_compiled_linear_system_func( morphism_1, morphism_2 ) );
 
-    v = NrColumns( Mt );
-    
-    s = NrColumns( It );
-    
-    if (s <= 1)
-        XX = TransposedMatrix( CertainRows( sol, [ 1.. v ] ) );
-    else
-        XX = TransposedMatrix( UnionOfColumns( List( (1):(s), i-> CertainRows( sol, [ (i-1)*v+1.. i*v ] ) ) ) );
-    end;
+    XX_tr = ConvertColumnToMatrix( CertainRows( sol, (1):(v * s) ), v, s );
 
-    return PresentationMorphism( cat, Range( morphism_1 ), XX, Range( morphism_2 ) );
+    return PresentationMorphism( cat, Range( morphism_1 ), TransposedMatrix( XX_tr ), Range( morphism_2 ) );
 
   end, 1000 );