Find faults in the following arguments, with brief explanations: (a) First faulty argument: 2(2) (3x) F(x) 3 (3) F(a) (4) F(a)→G(a) 1,3 (5) G(a) 1,3 (6) (Vr) G(x) 1,2 (7) (Vr) G(x) 3,4 MP 2,3,6 3 E (b) Second faulty argument: (1) (yz)(33) H(z, y) 1 (2) y) H(a, y)
(3) (4) 5(5) 4.5 (6) 4.5 (7) (3) H(by) H(a, b) H(b, a) H (a, b) ЛНФа) (3y)(H(a,y) ΛΗ(y, a)) 4,5 л! 6ヨ1 Now find models to demonstrate that the following sequents are not valid, with brief explanations: G(x)) , (yr) (F(x) (c) (3x) F(x) (#) G(x)