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| Mirrors > Home > MPE Home > Th. List > pnfxr | Structured version Visualization version Unicode version | ||
| Description: Plus infinity belongs to the set of extended reals. (Contributed by NM, 13-Oct-2005.) (Proof shortened by Anthony Hart, 29-Aug-2011.) |
| Ref | Expression |
|---|---|
| pnfxr |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ssun2 3777 |
. . 3
| |
| 2 | df-pnf 10076 |
. . . . 5
| |
| 3 | cnex 10017 |
. . . . . . 7
| |
| 4 | 3 | uniex 6953 |
. . . . . 6
|
| 5 | 4 | pwex 4848 |
. . . . 5
|
| 6 | 2, 5 | eqeltri 2697 |
. . . 4
|
| 7 | 6 | prid1 4297 |
. . 3
|
| 8 | 1, 7 | sselii 3600 |
. 2
|
| 9 | df-xr 10078 |
. 2
| |
| 10 | 8, 9 | eleqtrri 2700 |
1
|
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