Problem: (P > Q) ⊢ (P > (A > Q)) 1 |_ (P > Q) Premise 2 | |_ P Assumption 3 | | |_ A Assumption 4 | | | Q 1,2 >E 5 | | (A > Q) 3-4 >I 6 | (P > (A > Q)) 2-5 >I Problem: (A v B) ⊢ ~(~A & ~B) 1 |_ (A v B) Premise 2 | |_ (~A & ~B) Assumption 3 | | |_ A Assumption 4 | | | ~A 2 &E 5 | | | # 3,4 #I 6 | | |_ B Assumption 7 | | | ~B 2 &E 8 | | | # 6,7 #I 9 | | # 1,3-5,6-8 vE 10 | ~(~A & ~B) 2-9 ~I Problem: (A v (Ex)Fx) ⊢ (Ex)(A v Fx) 1 |_ (A v (Ex)Fx) Premise 2 | |_ A Assumption 3 | | (A v Fa) 2 vI 4 | | (Ex)(A v Fx) 3 EI 5 | |_ (Ex)Fx Assumption 6 | | |_ Fa Assumption 7 | | | (A v Fa) 6 vI 8 | | | (Ex)(A v Fx) 7 EI 9 | | (Ex)(A v Fx) 5,6-8 EE 10 | (Ex)(A v Fx) 1,2-4,5-9 vE Problem: ⊢ (Ax)(Ay)((Fx & ~Fy) > ~x=y) 1 |_ a Flag 2 | |_ b Flag 3 | | |_ (Fa & ~Fb) Assumption 4 | | | |_ a=b Assumption 5 | | | | Fa 3 &E 6 | | | | ~Fb 3 &E 7 | | | | Fb 4,5 =E 8 | | | | # 6,7 #I 9 | | | ~a=b 4-8 ~I 10 | | ((Fa & ~Fb) > ~a=b) 3-9 >I 11 | (Ay)((Fa & ~Fy) > ~a=y) 2-10 AI 12 (Ax)(Ay)((Fx & ~Fy) > ~x=y) 1-11 AI