InverseDerivations( X, i )
When T[i]
is a regular derivation, this function returns the
position j
such that T[j]
is the inverse of T[i]
in the
Whitehead group. When T[i]
is not regular, a list of values j
is
returned such that the inverse semigroup condition xyx = x, ; yxy =
y is satisfied, where x = T[i], y = T[j]. Notice that derivation 8
has order 3 and derivation 15 as inverse.
gap> inv4 := InverseDerivations( chi4 ); [ 4 ] gap> inv8 := InverseDerivations( chi8 ); [ 7, 8, 9 ]
GAP 3.4.4