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| Mirrors > Home > MPE Home > Th. List > nnm1nn0 | Structured version Visualization version Unicode version | ||
| Description: A positive integer minus 1 is a nonnegative integer. (Contributed by Jason Orendorff, 24-Jan-2007.) (Revised by Mario Carneiro, 16-May-2014.) |
| Ref | Expression |
|---|---|
| nnm1nn0 |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nn1m1nn 11040 |
. . . 4
| |
| 2 | oveq1 6657 |
. . . . . 6
| |
| 3 | 1m1e0 11089 |
. . . . . 6
| |
| 4 | 2, 3 | syl6eq 2672 |
. . . . 5
|
| 5 | 4 | orim1i 539 |
. . . 4
|
| 6 | 1, 5 | syl 17 |
. . 3
|
| 7 | 6 | orcomd 403 |
. 2
|
| 8 | elnn0 11294 |
. 2
| |
| 9 | 7, 8 | sylibr 224 |
1
|
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