Description: Cancellation law for the shift operation. (Contributed by NM, 4-Aug-2005) (Revised by Mario Carneiro, 5-Nov-2013)
Ref | Expression | ||
---|---|---|---|
Hypothesis | shftfval.1 | |
|
Assertion | shftcan2 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | shftfval.1 | |
|
2 | negneg | |
|
3 | 2 | adantr | |
4 | 3 | oveq2d | |
5 | 4 | fveq1d | |
6 | negcl | |
|
7 | 1 | shftcan1 | |
8 | 6 7 | sylan | |
9 | 5 8 | eqtr3d | |