50.24 CollapsedMat

CollapsedMat( mat, maps )

returns a record with fields mat and fusion: The fusion field contains the fusion that collapses the columns of mat that are identical also for all maps in the list maps, the mat field contains the image of mat under that fusion.

    gap> t.irreducibles;
    [ [ 1, 1, 1, 1, 1 ], [ 3, -1, 0, -E(5)-E(5)^4, -E(5)^2-E(5)^3 ],
      [ 3, -1, 0, -E(5)^2-E(5)^3, -E(5)-E(5)^4 ], [ 4, 0, 1, -1, -1 ],
      [ 5, 1, -1, 0, 0 ] ]
    gap> t:= CharTable( "A5" );; RationalizedMat( t.irreducibles );
    [ [ 1, 1, 1, 1, 1 ], [ 6, -2, 0, 1, 1 ], [ 4, 0, 1, -1, -1 ],
      [ 5, 1, -1, 0, 0 ] ]
    gap> CollapsedMat( last, [] );
    rec(
      mat := [ [ 1, 1, 1, 1 ], [ 6, -2, 0, 1 ], [ 4, 0, 1, -1 ],
          [ 5, 1, -1, 0 ] ],
      fusion := [ 1, 2, 3, 4, 4 ] )
    gap> Restricted( last.mat, last.fusion );
    [ [ 1, 1, 1, 1, 1 ], [ 6, -2, 0, 1, 1 ], [ 4, 0, 1, -1, -1 ],
      [ 5, 1, -1, 0, 0 ] ]

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