The preposition by projects an agentive adverbial phrase; is is a functor over (post)nominal modifiers (the man outside, John is outside, etc.)
~xVy(love y x) b. Vy3x(love y x) while the dominant reading of (7a) is (8a), that of (7b) is (8b), i.e., the preference is for the first quantifier to have wider scope.