YES Certificate: (0 (rr2 (product (nf (0)) (nf (0))) 0 1) (rr2 (product (nf (0)) (nf (0))) 0 1)) (1 (rr2 (equality) 0 1) (rr2 (equality) 0 1)) (2 (not 1) (not (rr2 (equality) 0 1))) (3 (and (0 2)) (and ((rr2 (product (nf (0)) (nf (0))) 0 1) (not (rr2 (equality) 0 1))))) (4 (rr2 (step* (0 0-)) 0 1) (rr2 (step* (0 0-)) 0 1)) (5 (and (3 4)) (and ((and ((rr2 (product (nf (0)) (nf (0))) 0 1) (not (rr2 (equality) 0 1)))) (rr2 (step* (0 0-)) 0 1)))) (6 (exists 5) (exists (and ((and ((rr2 (product (nf (0)) (nf (0))) 0 1) (not (rr2 (equality) 0 1)))) (rr2 (step* (0 0-)) 0 1))))) (7 (exists 6) (exists (exists (and ((and ((rr2 (product (nf (0)) (nf (0))) 0 1) (not (rr2 (equality) 0 1)))) (rr2 (step* (0 0-)) 0 1)))))) (8 (not 7) (not (exists (exists (and ((and ((rr2 (product (nf (0)) (nf (0))) 0 1) (not (rr2 (equality) 0 1)))) (rr2 (step* (0 0-)) 0 1))))))) (9 (nnf 8) (forall (forall (or ((not (and ((rr2 (product (nf (0)) (nf (0))) 0 1) (not (rr2 (equality) 0 1))))) (not (rr2 (step* (0 0-)) 0 1))))))) (nonempty 9)