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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 7561 | . 2 ⊢ 2𝑜 = suc 1𝑜 | |
2 | 1onn 7719 | . . 3 ⊢ 1𝑜 ∈ ω | |
3 | peano2 7086 | . . 3 ⊢ (1𝑜 ∈ ω → suc 1𝑜 ∈ ω) | |
4 | 2, 3 | ax-mp 5 | . 2 ⊢ suc 1𝑜 ∈ ω |
5 | 1, 4 | eqeltri 2697 | 1 ⊢ 2𝑜 ∈ ω |
Colors of variables: wff setvar class |
Syntax hints: ∈ wcel 1990 suc csuc 5725 ωcom 7065 1𝑜c1o 7553 2𝑜c2o 7554 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1722 ax-4 1737 ax-5 1839 ax-6 1888 ax-7 1935 ax-8 1992 ax-9 1999 ax-10 2019 ax-11 2034 ax-12 2047 ax-13 2246 ax-ext 2602 ax-sep 4781 ax-nul 4789 ax-pr 4906 ax-un 6949 |
This theorem depends on definitions: df-bi 197 df-or 385 df-an 386 df-3or 1038 df-3an 1039 df-tru 1486 df-ex 1705 df-nf 1710 df-sb 1881 df-eu 2474 df-mo 2475 df-clab 2609 df-cleq 2615 df-clel 2618 df-nfc 2753 df-ne 2795 df-ral 2917 df-rex 2918 df-rab 2921 df-v 3202 df-sbc 3436 df-dif 3577 df-un 3579 df-in 3581 df-ss 3588 df-pss 3590 df-nul 3916 df-if 4087 df-pw 4160 df-sn 4178 df-pr 4180 df-tp 4182 df-op 4184 df-uni 4437 df-br 4654 df-opab 4713 df-tr 4753 df-eprel 5029 df-po 5035 df-so 5036 df-fr 5073 df-we 5075 df-ord 5726 df-on 5727 df-lim 5728 df-suc 5729 df-om 7066 df-1o 7560 df-2o 7561 |
This theorem is referenced by: 3onn 7721 nn2m 7730 nnneo 7731 nneob 7732 omopthlem1 7735 omopthlem2 7736 pwen 8133 en3 8197 en2eqpr 8830 en2eleq 8831 unctb 9027 infcdaabs 9028 ackbij1lem5 9046 sdom2en01 9124 fin56 9215 fin67 9217 fin1a2lem4 9225 alephexp1 9401 pwcfsdom 9405 alephom 9407 canthp1lem2 9475 pwxpndom2 9487 hash3 13194 hash2pr 13251 pr2pwpr 13261 rpnnen 14956 rexpen 14957 xpsfrnel 16223 symggen 17890 psgnunilem1 17913 znfld 19909 hauspwdom 21304 xpsmet 22187 xpsxms 22339 xpsms 22340 1oequni2o 33216 finxpreclem4 33231 finxp3o 33237 wepwso 37613 frlmpwfi 37668 |
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