premise: A man is standing at a machine.
hypothesis: A man is standing by a machine.
explanation_1: The man is by a machine because he is at a machine.
explanation_2: Standing at a machine implies standing by it.
explanation_3: The man is standing by a machine because he is standing at a machine.
premise_logic: exists e1 x1 x2.(at(e1,x2) & n_machine(x2) & Actor(e1,x1) & v_stand(e1) & n_man(x1))
hypothesis_logic: exists e1 x1 x2.(by(e1,x2) & n_machine(x2) & Actor(e1,x1) & v_stand(e1) & n_man(x1))