7. And-Elim
| A and B.
|---------
| A.
| B.
assert A and B
assert A
assert B
8. Or-Intro
| A.
|---------
| A or B.
| B or A.
assert A
assert A or B
assert B or A
9. Or-Elim
| A or B.
| If A:
| C.
| If B:
| C.
|---------
| C.
assert A or B
if A:
assert C
if B:
assert C
assert C