Proof: Add Insn 22
Let's prove the following theorem:
if the following are true:
- the PC at time 22 = 4
- instruction #4 is
add dst=3 src1=1 src2=2
then value of cell 3 at time 23 = (value of cell 1 at time 22) + (value of cell 2 at time 22)
Instructions
Memory Cells |
---|
Program Counter | Time |
---|---|
0 | 0 |
LW Computer Simulator
Proof:
Given
1 | the PC at time 22 = 4 |
---|---|
2 | instruction #4 is add dst=3 src1=1 src2=2 |
# | Claim | Reason |
---|---|---|
1 | value of cell 3 at time (22 + 1) = (value of cell 1 at time 22) + (value of cell 2 at time 22) | if instruction #4 is add dst=3 src1=1 src2=2 and the PC at time 22 = 4, then value of cell 3 at time (22 + 1) = (value of cell 1 at time 22) + (value of cell 2 at time 22) |
2 | 22 + 1 = 23 | 22 + 1 = 23 |
3 | value of cell 3 at time (22 + 1) = value of cell 3 at time 23 | if 22 + 1 = 23, then value of cell 3 at time (22 + 1) = value of cell 3 at time 23 |
4 | value of cell 3 at time 23 = (value of cell 1 at time 22) + (value of cell 2 at time 22) | if value of cell 3 at time (22 + 1) = value of cell 3 at time 23 and value of cell 3 at time (22 + 1) = (value of cell 1 at time 22) + (value of cell 2 at time 22), then value of cell 3 at time 23 = (value of cell 1 at time 22) + (value of cell 2 at time 22) |
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