Solutions to Easy Proofs in QL
Proof 5
1.
(x)(Rx v ~Sx)
premise
2.
(x)(~Sx
⊃
Tx)
premise
3.
~Ta
premise
4.
~Sa
⊃
Ta
U.I., 2
5.
~~Sa
M.T. 3,4
6.
Ra v ~Sa
U.I., 1
7.
Ra
D.S., 5,6
8.
(
∃
x)Rx
E.G., 7