73.105 SourceEndomorphismDerivation

SourceEndomorphismDerivation( chi )

Each derivation chi determines an endomorphism sigma of S such that sigma s = s (chi partial s). This construction defines a homomorphism from the Whitehead group to Aut(S) which forms the action homomorphism of the Whitehead crossed module described in section refWhitehead crossed module.

    gap> sigma8 := SourceEndomorphismDerivation( chi8 );
    GroupHomomorphismByImages( c3, c3, [ (1,2,3)(4,6,5) ], [ () ] )
    gap> sigma4 := SourceEndomorphismDerivation( chi4 );
    GroupHomomorphismByImages( c3, c3, [ (1,2,3)(4,6,5) ], 
       [ (1,3,2)(4,5,6) ] ) 

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