Premise: Perhaps the Proximity people thought that they had got round that little problem by giving the same definition for each of the items in the list; but we know that only very rarely are two synonyms bi-unique (which is another way of saying that if A = B, B does not necessarily always equal A), an ineluctable fact of language.

Hypothesis: Just because x equals y, you can't assume that y and x are always identical.
Relation: entailment