![]() |
Metamath Proof Explorer |
< Previous
Next >
Nearby theorems |
|
Mirrors > Home > MPE Home > Th. List > peano1 | Structured version Visualization version GIF version |
Description: Zero is a natural number. One of Peano's five postulates for arithmetic. Proposition 7.30(1) of [TakeutiZaring] p. 42. Note: Unlike most textbooks, our proofs of peano1 7910 through peano5 7915 do not use the Axiom of Infinity. Unlike Takeuti and Zaring, they also do not use the Axiom of Regularity. (Contributed by NM, 15-May-1994.) Avoid ax-un 7753. (Revised by BTernaryTau, 29-Nov-2024.) |
Ref | Expression |
---|---|
peano1 | ⊢ ∅ ∈ ω |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0elon 6439 | . 2 ⊢ ∅ ∈ On | |
2 | 0ellim 6448 | . . 3 ⊢ (Lim 𝑥 → ∅ ∈ 𝑥) | |
3 | 2 | ax-gen 1791 | . 2 ⊢ ∀𝑥(Lim 𝑥 → ∅ ∈ 𝑥) |
4 | elom 7889 | . 2 ⊢ (∅ ∈ ω ↔ (∅ ∈ On ∧ ∀𝑥(Lim 𝑥 → ∅ ∈ 𝑥))) | |
5 | 1, 3, 4 | mpbir2an 711 | 1 ⊢ ∅ ∈ ω |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∀wal 1534 ∈ wcel 2105 ∅c0 4338 Oncon0 6385 Lim wlim 6386 ωcom 7886 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1791 ax-4 1805 ax-5 1907 ax-6 1964 ax-7 2004 ax-8 2107 ax-9 2115 ax-ext 2705 ax-sep 5301 ax-nul 5311 ax-pr 5437 |
This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3or 1087 df-3an 1088 df-tru 1539 df-fal 1549 df-ex 1776 df-sb 2062 df-clab 2712 df-cleq 2726 df-clel 2813 df-ne 2938 df-ral 3059 df-rex 3068 df-rab 3433 df-v 3479 df-dif 3965 df-un 3967 df-in 3969 df-ss 3979 df-pss 3982 df-nul 4339 df-if 4531 df-pw 4606 df-sn 4631 df-pr 4633 df-op 4637 df-uni 4912 df-br 5148 df-opab 5210 df-tr 5265 df-eprel 5588 df-po 5596 df-so 5597 df-fr 5640 df-we 5642 df-ord 6388 df-on 6389 df-lim 6390 df-om 7887 |
This theorem is referenced by: onnseq 8382 rdg0 8459 fr0g 8474 seqomlem3 8490 oa1suc 8567 o2p2e4 8577 om1 8578 oe1 8580 nna0r 8645 nnm0r 8646 nnmcl 8648 nnecl 8649 nnmsucr 8661 nnaword1 8665 nnaordex 8674 1onnALT 8677 oaabs2 8685 nnm1 8688 nneob 8692 omopth 8698 0fi 9080 snfiOLD 9082 0finOLD 9208 0sdom1domALT 9272 isinf 9293 nnunifi 9324 unblem2 9326 infn0 9337 infn0ALT 9338 unfilem3 9342 dffi3 9468 inf0 9658 infeq5i 9673 axinf2 9677 dfom3 9684 infdifsn 9694 noinfep 9697 cantnflt 9709 cnfcomlem 9736 cnfcom 9737 cnfcom2lem 9738 cnfcom3lem 9740 cnfcom3 9741 brttrcl2 9751 ttrcltr 9753 rnttrcl 9759 trcl 9765 rankdmr1 9838 rankeq0b 9897 cardlim 10009 infxpenc 10055 infxpenc2 10059 alephgeom 10119 alephfplem4 10144 ackbij1lem13 10268 ackbij1 10274 ackbij1b 10275 ominf4 10349 fin23lem16 10372 fin23lem31 10380 fin23lem40 10388 isf32lem9 10398 isf34lem7 10416 isf34lem6 10417 fin1a2lem6 10442 fin1a2lem7 10443 fin1a2lem11 10447 axdc3lem2 10488 axdc3lem4 10490 axdc4lem 10492 axcclem 10494 axdclem2 10557 pwfseqlem5 10700 omina 10728 wunex3 10778 1lt2pi 10942 1nn 12274 om2uzrani 13989 uzrdg0i 13996 fzennn 14005 axdc4uzlem 14020 hash1 14439 fnpr2o 17603 fvpr0o 17605 ltbwe 22079 2ndcdisj2 23480 precsexlem11 28255 noseq0 28310 noseqrdg0 28327 n0sbday 28368 dfnns2 28376 snct 32730 goelel3xp 35332 satfv0 35342 satfv1 35347 satf0 35356 satf00 35358 satf0suclem 35359 sat1el2xp 35363 fmla0 35366 fmlasuc0 35368 fmla1 35371 gonan0 35376 gonar 35379 goalr 35381 satffunlem1lem2 35387 satffunlem1 35391 satefvfmla0 35402 prv0 35414 nnuni 35706 0hf 36158 neibastop2lem 36342 bj-rdg0gALT 37053 rdgeqoa 37352 exrecfnlem 37361 finxp0 37373 onexomgt 43229 onexoegt 43232 omnord1 43294 oenord1 43305 oaomoencom 43306 cantnftermord 43309 cantnfub 43310 cantnf2 43314 dflim5 43318 oacl2g 43319 onmcl 43320 omabs2 43321 omcl2 43322 tfsconcat0b 43335 ofoaf 43344 ofoafo 43345 ofoaid1 43347 ofoaid2 43348 naddcnff 43351 naddcnffo 43353 naddcnfid1 43356 naddcnfid2 43357 0finon 43437 0iscard 43530 |
Copyright terms: Public domain | W3C validator |