Relation SUBSET

The sentence {tt (subset $tau_1$ $tau_2$)} is true if and only if $tau_1$ and $tau_2$ are sets and the objects in the set denoted by $tau_1$ are contained in the set denoted by $tau_2$.
Arity: 2
Domain: Set
Range: Set
Axioms:
(<=> (Subset ?S1 ?S2)
     (And (Set ?S1)
          (Set ?S2)
          (Forall (?X) (=> (Member ?X ?S1) (Member ?X ?S2)))))