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Mirrors > Home > MPE Home > Th. List > pnfxr | Structured version Visualization version GIF 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 | ⊢ +∞ ∈ ℝ* |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ssun2 3777 | . . 3 ⊢ {+∞, -∞} ⊆ (ℝ ∪ {+∞, -∞}) | |
2 | df-pnf 10076 | . . . . 5 ⊢ +∞ = 𝒫 ∪ ℂ | |
3 | cnex 10017 | . . . . . . 7 ⊢ ℂ ∈ V | |
4 | 3 | uniex 6953 | . . . . . 6 ⊢ ∪ ℂ ∈ V |
5 | 4 | pwex 4848 | . . . . 5 ⊢ 𝒫 ∪ ℂ ∈ V |
6 | 2, 5 | eqeltri 2697 | . . . 4 ⊢ +∞ ∈ V |
7 | 6 | prid1 4297 | . . 3 ⊢ +∞ ∈ {+∞, -∞} |
8 | 1, 7 | sselii 3600 | . 2 ⊢ +∞ ∈ (ℝ ∪ {+∞, -∞}) |
9 | df-xr 10078 | . 2 ⊢ ℝ* = (ℝ ∪ {+∞, -∞}) | |
10 | 8, 9 | eleqtrri 2700 | 1 ⊢ +∞ ∈ ℝ* |
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