const In : set set prop term iIn = In infix iIn 2000 2000 term Subq = \x:set.\y:set.!z:set.z iIn x -> z iIn y const binintersect : set set set axiom binintersect_Subq_1: !x:set.!y:set.Subq (binintersect x y) x axiom binintersectI: !x:set.!y:set.!z:set.z iIn x -> z iIn y -> z iIn binintersect x y axiom set_ext: !x:set.!y:set.Subq x y -> Subq y x -> x = y claim !x:set.!y:set.Subq x y -> binintersect x y = x