1.
2.
3.
/S
See also:
Implication
Formal Proof
Well Formed
Validity
mp
>
(A & B)
(~D + S)
D
A & B
4.
1,3 MP
1. Find a line with implication as a main connective.
2. Pick out the left sub-expression.
3. Scan lines to find a match for the left sub-expression.
4. Append a new line which shows the you've derived the right sub-expression of line 1 from 1 & 3 by MP