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Mirrors > Home > ILE Home > Th. List > pp0ex | GIF version |
Description: {∅, {∅}} (the ordinal 2) is a set. (Contributed by NM, 5-Aug-1993.) |
Ref | Expression |
---|---|
pp0ex | ⊢ {∅, {∅}} ∈ V |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | p0ex 3939 | . . 3 ⊢ {∅} ∈ V | |
2 | 1 | pwex 3932 | . 2 ⊢ 𝒫 {∅} ∈ V |
3 | pwpw0ss 3575 | . 2 ⊢ {∅, {∅}} ⊆ 𝒫 {∅} | |
4 | 2, 3 | ssexi 3895 | 1 ⊢ {∅, {∅}} ∈ V |
Colors of variables: wff set class |
Syntax hints: ∈ wcel 1393 Vcvv 2557 ∅c0 3224 𝒫 cpw 3359 {csn 3375 {cpr 3376 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 99 ax-ia2 100 ax-ia3 101 ax-in1 544 ax-in2 545 ax-io 630 ax-5 1336 ax-7 1337 ax-gen 1338 ax-ie1 1382 ax-ie2 1383 ax-8 1395 ax-10 1396 ax-11 1397 ax-i12 1398 ax-bndl 1399 ax-4 1400 ax-14 1405 ax-17 1419 ax-i9 1423 ax-ial 1427 ax-i5r 1428 ax-ext 2022 ax-sep 3875 ax-nul 3883 ax-pow 3927 |
This theorem depends on definitions: df-bi 110 df-tru 1246 df-nf 1350 df-sb 1646 df-clab 2027 df-cleq 2033 df-clel 2036 df-nfc 2167 df-v 2559 df-dif 2920 df-un 2922 df-in 2924 df-ss 2931 df-nul 3225 df-pw 3361 df-sn 3381 df-pr 3382 |
This theorem is referenced by: ord3ex 3941 ontr2exmid 4250 ordtri2or2exmidlem 4251 onsucelsucexmidlem 4254 regexmid 4260 reg2exmid 4261 reg3exmid 4304 nnregexmid 4342 acexmidlemcase 5507 acexmidlemv 5510 |
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