If a map 
from a group 
to a group 
satisfies 
for all 
, then 
is said to be an antihomomorphism.
Moreover, if 
and 
are isomorphic, then 
is said to be an antiautomorphism.
Antiautomorphism
See also
Antihomomorphism, AutomorphismExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Antiautomorphism." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Antiautomorphism.html