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| Description: The successor of any natural number is a natural number. One of Peano's 5 postulates for arithmetic. Proposition 7.30(2) of [TakeutiZaring] p. 42. |
| Ref | Expression |
|---|---|
| peano2 |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | peano2b 3779 |
. 2
| |
| 2 | 1 | biimpi 167 |
1
|
| Colors of variables: wff set class |
| Syntax hints: |
| This theorem is referenced by: nnacl 5092 nnaclOLD 5093 nnecl 5096 nneclOLD 5097 nnmsucr 5106 1onn 5121 2onn 5122 unbnn2 5448 axinf2 5539 dfom3 5546 noinfep 5556 trcl 5561 cardsucnn 5667 omsublim 5683 alephfp 5844 om2uzrani 7506 uzrdgsuci 7511 cardfz 7514 dif1en 9966 dif1enOLD 9967 dif1card 9969 findcard 9970 findcardOLD 9971 bnj924 12625 trcltr 13728 top2usne 14618 fictblem 15052 omsublimOLD 15078 neibastop2lem4 15204 findcard2 15427 |
| This theorem was proved from axioms: ax-1 4 ax-2 5 ax-3 6 ax-mp 7 ax-7 1142 ax-gen 1143 ax-8 1144 ax-9 1145 ax-10 1146 ax-11 1147 ax-12 1148 ax-13 1149 ax-14 1150 ax-17 1155 ax-4 1157 ax-5o 1159 ax-6o 1162 ax-9o 1319 ax-10o 1338 ax-16 1418 ax-11o 1426 ax-ext 1702 ax-sep 3253 ax-nul 3260 ax-pow 3296 ax-pr 3339 ax-un 3601 |
| This theorem depends on definitions: df-bi 163 df-or 240 df-an 241 df-3or 856 df-3an 857 df-ex 1165 df-sb 1374 df-eu 1613 df-mo 1614 df-clab 1709 df-cleq 1714 df-clel 1717 df-ne 1856 df-ral 1943 df-rex 1944 df-rab 1946 df-v 2127 df-dif 2430 df-un 2433 df-in 2436 df-ss 2438 df-pss 2440 df-nul 2702 df-if 2807 df-pw 2859 df-sn 2873 df-pr 2874 df-tp 2876 df-op 2877 df-uni 3000 df-br 3159 df-opab 3214 df-tr 3230 df-eprel 3398 df-po 3406 df-so 3419 df-fr 3440 df-we 3459 df-ord 3475 df-on 3476 df-lim 3477 df-suc 3478 df-om 3761 |