Sentence:  The standard example for an <WSD>antisymmetric</WSD> relation is the relation less than or equal to on the real number system. 
Meaning of the word marked with <WSD> tags:  Having the property that, for any two distinct elements of "S", at least one is not related to the other via "R"; "equivalently", having the property that, for any "x, y" ∈ "S", if both "xRy" and "yRx" then "x"="y".