Proofs of the Valid Sequents, Test #2 Review

 Please let me know if you find any typos.


S v ~T <-> ~R, ~(Q v P) -> T, ~Q |- P v (R v S)

 

1          (1) S v ~T <-> ~R           A

2          (2) ~(Q v P) -> T           A

3          (3) ~Q                      A

4          (4) ~(P v (R v S))          A [for RAA]

4          (5) ~P & ~(R v S)           4 DM

4          (6) ~(R v S)                5 &E

4          (7) ~R & ~S                 6 DM

4          (8) ~R                      7 &E

1,4        (9) S v ~T                  1,8 BP

4          (10) ~S                     7 &E

1,4        (11) ~T                     9,10 vE

1,2        (12) Q v P                  2,11 MTT

1,2,3      (13) P                      3,12 vE

4          (14) ~P                     5 &E

1,2,3      (15) P v (R v S)            13,14 RAA (4)


 
(P & Q) v (R & S) |- P v R
 
1    (1) (P & Q) v (R & S)   A
2    (2) ~(P v R)            A [for RAA]
2    (3) ~P & ~R             2 DM
2    (4) ~P                  3 &E
2    (5) ~P v ~Q             4 vI
2    (6) ~(P & Q)            5 DM
1,2  (7) R & S               1,6 vE
1,2  (8) R                   7 &E
2    (9) ~R                  3 &E
1    (10) P v R              8,9 RAA (2)


 
~(P -> Q), R v Q |- ~(P & R) -> S
 
1    (1) ~(P -> Q)            A
2    (2) R v Q                A
3    (3) ~(P & R)             A [for ->I]
3    (4) ~P v ~R              3 DM
1    (5) P & ~Q               1 Neg->
1    (6) P                    5 &E
1,3  (7) ~R                   4,6 vE
1,2,3(8) Q                    2,7 vE
1    (9) ~Q                   5 &E
10   (10) ~S                  A [for RAA]
1,2,3(11) S                   8,9 RAA (10)
1,2  (12) ~(P & R) -> S       11 ->I (3)
 

 
R v S -> Q, ~P -> ~R |- ~R v (P <-> Q)
 
1    (1) R v S -> Q           A
2    (2) ~P -> ~R             A
3    (3) ~(~R v (P <-> Q))    A
3    (4) R & ~(P <-> Q)       3 DM
3    (5) R                    4 &E
3    (6) ~(P <-> Q)           4 &E
3    (7) P <-> ~Q             6 Neg<->
3    (8) R v S                5 vI
1,3  (9) Q                    1,8 vE
2,3  (10) P                   2,5 MTT
2,3  (11) ~Q                  7,10 BP
1,2  (12) ~R v (P <-> Q)      9,11 RAA (3)