let X be non empty set ; :: thesis: for R being Relation of X st R is_antisymmetric_in X holds
R is antisymmetric
let R be Relation of X; :: thesis: ( R is_antisymmetric_in X implies R is antisymmetric )
assume A1: R is_antisymmetric_in X ; :: thesis: R is antisymmetric
let x, y be object ; :: according to RELAT_2:def 4,RELAT_2:def 12 :: thesis: ( not x in field R or not y in field R or not [x,y] in R or not [y,x] in R or x = y )
field R c= X \/ X by RELSET_1:8;
hence ( not x in field R or not y in field R or not [x,y] in R or not [y,x] in R or x = y ) by A1; :: thesis: verum