x1 is a binary relation which is right-Euclidean on space/set/under conditions x2.
Definitionally, x1 is an ordered binary relation given by set R such that for all a, b, c in x2 (if such makes sense; else: the universe of discourse restricted by x2), if (a, b) in R and (a, c) in R, then (b, c) in R and (c, b) in R. See also: "takni", ".efklizu".