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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 7879 through peano5 7884 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 7725. (Revised by BTernaryTau, 29-Nov-2024.) |
Ref | Expression |
---|---|
peano1 | ⊢ ∅ ∈ ω |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0elon 6419 | . 2 ⊢ ∅ ∈ On | |
2 | 0ellim 6428 | . . 3 ⊢ (Lim 𝑥 → ∅ ∈ 𝑥) | |
3 | 2 | ax-gen 1798 | . 2 ⊢ ∀𝑥(Lim 𝑥 → ∅ ∈ 𝑥) |
4 | elom 7858 | . 2 ⊢ (∅ ∈ ω ↔ (∅ ∈ On ∧ ∀𝑥(Lim 𝑥 → ∅ ∈ 𝑥))) | |
5 | 1, 3, 4 | mpbir2an 710 | 1 ⊢ ∅ ∈ ω |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∀wal 1540 ∈ wcel 2107 ∅c0 4323 Oncon0 6365 Lim wlim 6366 ωcom 7855 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1798 ax-4 1812 ax-5 1914 ax-6 1972 ax-7 2012 ax-8 2109 ax-9 2117 ax-ext 2704 ax-sep 5300 ax-nul 5307 ax-pr 5428 |
This theorem depends on definitions: df-bi 206 df-an 398 df-or 847 df-3or 1089 df-3an 1090 df-tru 1545 df-fal 1555 df-ex 1783 df-sb 2069 df-clab 2711 df-cleq 2725 df-clel 2811 df-ne 2942 df-ral 3063 df-rex 3072 df-rab 3434 df-v 3477 df-dif 3952 df-un 3954 df-in 3956 df-ss 3966 df-pss 3968 df-nul 4324 df-if 4530 df-pw 4605 df-sn 4630 df-pr 4632 df-op 4636 df-uni 4910 df-br 5150 df-opab 5212 df-tr 5267 df-eprel 5581 df-po 5589 df-so 5590 df-fr 5632 df-we 5634 df-ord 6368 df-on 6369 df-lim 6370 df-om 7856 |
This theorem is referenced by: onnseq 8344 rdg0 8421 fr0g 8436 seqomlem3 8452 oa1suc 8531 o2p2e4 8541 om1 8542 oe1 8544 nna0r 8609 nnm0r 8610 nnmcl 8612 nnecl 8613 nnmsucr 8625 nnaword1 8629 nnaordex 8638 1onnALT 8640 oaabs2 8648 nnm1 8651 nneob 8655 omopth 8661 snfi 9044 0fin 9171 0sdom1domALT 9239 isinf 9260 findcard2OLD 9284 nnunifi 9294 unblem2 9296 infn0 9307 infn0ALT 9308 unfilem3 9312 dffi3 9426 inf0 9616 infeq5i 9631 axinf2 9635 dfom3 9642 infdifsn 9652 noinfep 9655 cantnflt 9667 cnfcomlem 9694 cnfcom 9695 cnfcom2lem 9696 cnfcom3lem 9698 cnfcom3 9699 brttrcl2 9709 ttrcltr 9711 rnttrcl 9717 trcl 9723 rankdmr1 9796 rankeq0b 9855 cardlim 9967 infxpenc 10013 infxpenc2 10017 alephgeom 10077 alephfplem4 10102 ackbij1lem13 10227 ackbij1 10233 ackbij1b 10234 ominf4 10307 fin23lem16 10330 fin23lem31 10338 fin23lem40 10346 isf32lem9 10356 isf34lem7 10374 isf34lem6 10375 fin1a2lem6 10400 fin1a2lem7 10401 fin1a2lem11 10405 axdc3lem2 10446 axdc3lem4 10448 axdc4lem 10450 axcclem 10452 axdclem2 10515 pwfseqlem5 10658 omina 10686 wunex3 10736 1lt2pi 10900 1nn 12223 om2uzrani 13917 uzrdg0i 13924 fzennn 13933 axdc4uzlem 13948 hash1 14364 fnpr2o 17503 fvpr0o 17505 ltbwe 21599 2ndcdisj2 22961 precsexlem11 27663 snct 31938 goelel3xp 34339 satfv0 34349 satfv1 34354 satf0 34363 satf00 34365 satf0suclem 34366 sat1el2xp 34370 fmla0 34373 fmlasuc0 34375 fmla1 34378 gonan0 34383 gonar 34386 goalr 34388 satffunlem1lem2 34394 satffunlem1 34398 satefvfmla0 34409 prv0 34421 nnuni 34696 0hf 35149 neibastop2lem 35245 bj-rdg0gALT 35952 rdgeqoa 36251 exrecfnlem 36260 finxp0 36272 onexomgt 41990 onexoegt 41993 omnord1 42055 oenord1 42066 oaomoencom 42067 cantnftermord 42070 cantnfub 42071 cantnf2 42075 dflim5 42079 oacl2g 42080 onmcl 42081 omabs2 42082 omcl2 42083 tfsconcat0b 42096 ofoaf 42105 ofoafo 42106 ofoaid1 42108 ofoaid2 42109 naddcnff 42112 naddcnffo 42114 naddcnfid1 42117 naddcnfid2 42118 0finon 42199 0iscard 42292 |
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