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Mirrors > Home > MPE Home > Th. List > 2onn | Structured version Visualization version GIF version |
Description: The ordinal 2 is a natural number. (Contributed by NM, 28-Sep-2004.) |
Ref | Expression |
---|---|
2onn | ⊢ 2o ∈ ω |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-2o 8105 | . 2 ⊢ 2o = suc 1o | |
2 | 1onn 8267 | . . 3 ⊢ 1o ∈ ω | |
3 | peano2 7604 | . . 3 ⊢ (1o ∈ ω → suc 1o ∈ ω) | |
4 | 2, 3 | ax-mp 5 | . 2 ⊢ suc 1o ∈ ω |
5 | 1, 4 | eqeltri 2911 | 1 ⊢ 2o ∈ ω |
Colors of variables: wff setvar class |
Syntax hints: ∈ wcel 2114 suc csuc 6195 ωcom 7582 1oc1o 8097 2oc2o 8098 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2161 ax-12 2177 ax-ext 2795 ax-sep 5205 ax-nul 5212 ax-pr 5332 ax-un 7463 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1540 df-ex 1781 df-nf 1785 df-sb 2070 df-mo 2622 df-eu 2654 df-clab 2802 df-cleq 2816 df-clel 2895 df-nfc 2965 df-ne 3019 df-ral 3145 df-rex 3146 df-rab 3149 df-v 3498 df-sbc 3775 df-dif 3941 df-un 3943 df-in 3945 df-ss 3954 df-pss 3956 df-nul 4294 df-if 4470 df-pw 4543 df-sn 4570 df-pr 4572 df-tp 4574 df-op 4576 df-uni 4841 df-br 5069 df-opab 5131 df-tr 5175 df-eprel 5467 df-po 5476 df-so 5477 df-fr 5516 df-we 5518 df-ord 6196 df-on 6197 df-lim 6198 df-suc 6199 df-om 7583 df-1o 8104 df-2o 8105 |
This theorem is referenced by: 3onn 8269 nn2m 8279 nnneo 8280 nneob 8281 omopthlem1 8284 omopthlem2 8285 pwen 8692 en3 8757 en2eqpr 9435 en2eleq 9436 unctb 9629 infdjuabs 9630 ackbij1lem5 9648 sdom2en01 9726 fin56 9817 fin67 9819 fin1a2lem4 9827 alephexp1 10003 pwcfsdom 10007 alephom 10009 canthp1lem2 10077 pwxpndom2 10089 hash3 13770 hash2pr 13830 pr2pwpr 13840 rpnnen 15582 rexpen 15583 xpsfrnel 16837 xpscf 16840 symggen 18600 psgnunilem1 18623 simpgnsgd 19224 znfld 20709 hauspwdom 22111 xpsmet 22994 xpsxms 23146 xpsms 23147 unidifsnel 30297 unidifsnne 30298 sat1el2xp 32628 ex-sategoelelomsuc 32675 ex-sategoelel12 32676 1oequni2o 34651 finxpreclem4 34677 finxp3o 34683 wepwso 39650 frlmpwfi 39705 |
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