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7.7.9.0. isInvolution
Procedure from library involut.lib (see involut_lib).

Usage:
isInvolution(F); F is a map from current ring to itself

Return:
integer, 1 if F determines an involution and 0 otherwise

Theory:
involution is an antiautomorphism of order 2

Assume:
F is a map from current ring to itself

Example:
 
LIB "involut.lib";
def A = makeUsl(2); setring A;
map I = A,-e,-f,-h; //correct antiauto involution
isInvolution(I);
==> 1
map J = A,3*e,1/3*f,-h; // antiauto but not involution
isInvolution(J);
==> 0
map K = A,f,e,-h; // not antiauto
isInvolution(K);
==> 0
See also: findInvo; involution; isAntiEndo.