21.1 IsPermGroup

IsPermGroup( obj )

IsPermGroup returns true if the object obj, which may be an object of an arbitrary type, is a permutation group, and false otherwise. It will signal an error if obj is an unbound variable.

    gap> s4 := Group( (1,2), (1,2,3,4) );; s4.name := "s4";;
    gap> IsPermGroup( s4 );
    true
    gap> f := FactorGroup( s4, Subgroup( s4, [(1,2)(3,4),(1,3)(2,4)] ) );
    (s4 / Subgroup( s4, [ (1,2)(3,4), (1,3)(2,4) ] ))
    gap> IsPermGroup( f );
    false    # see section "FactorGroup"
    gap> IsPermGroup( [ 1, 2 ] );
    false 

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