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Theorem nnind 11076
 Description: Principle of Mathematical Induction (inference schema). The first four hypotheses give us the substitution instances we need; the last two are the basis and the induction step. See nnaddcl 11080 for an example of its use. See nn0ind 11510 for induction on nonnegative integers and uzind 11507, uzind4 11784 for induction on an arbitrary upper set of integers. See indstr 11794 for strong induction. See also nnindALT 11077. This is an alternative for Metamath 100 proof #74. (Contributed by NM, 10-Jan-1997.) (Revised by Mario Carneiro, 16-Jun-2013.)
Hypotheses
Ref Expression
nnind.1 (𝑥 = 1 → (𝜑𝜓))
nnind.2 (𝑥 = 𝑦 → (𝜑𝜒))
nnind.3 (𝑥 = (𝑦 + 1) → (𝜑𝜃))
nnind.4 (𝑥 = 𝐴 → (𝜑𝜏))
nnind.5 𝜓
nnind.6 (𝑦 ∈ ℕ → (𝜒𝜃))
Assertion
Ref Expression
nnind (𝐴 ∈ ℕ → 𝜏)
Distinct variable groups:   𝑥,𝑦   𝑥,𝐴   𝜓,𝑥   𝜒,𝑥   𝜃,𝑥   𝜏,𝑥   𝜑,𝑦
Allowed substitution hints:   𝜑(𝑥)   𝜓(𝑦)   𝜒(𝑦)   𝜃(𝑦)   𝜏(𝑦)   𝐴(𝑦)

Proof of Theorem nnind
StepHypRef Expression
1 1nn 11069 . . . . . 6 1 ∈ ℕ
2 nnind.5 . . . . . 6 𝜓
3 nnind.1 . . . . . . 7 (𝑥 = 1 → (𝜑𝜓))
43elrab 3396 . . . . . 6 (1 ∈ {𝑥 ∈ ℕ ∣ 𝜑} ↔ (1 ∈ ℕ ∧ 𝜓))
51, 2, 4mpbir2an 975 . . . . 5 1 ∈ {𝑥 ∈ ℕ ∣ 𝜑}
6 elrabi 3391 . . . . . . 7 (𝑦 ∈ {𝑥 ∈ ℕ ∣ 𝜑} → 𝑦 ∈ ℕ)
7 peano2nn 11070 . . . . . . . . . 10 (𝑦 ∈ ℕ → (𝑦 + 1) ∈ ℕ)
87a1d 25 . . . . . . . . 9 (𝑦 ∈ ℕ → (𝑦 ∈ ℕ → (𝑦 + 1) ∈ ℕ))
9 nnind.6 . . . . . . . . 9 (𝑦 ∈ ℕ → (𝜒𝜃))
108, 9anim12d 585 . . . . . . . 8 (𝑦 ∈ ℕ → ((𝑦 ∈ ℕ ∧ 𝜒) → ((𝑦 + 1) ∈ ℕ ∧ 𝜃)))
11 nnind.2 . . . . . . . . 9 (𝑥 = 𝑦 → (𝜑𝜒))
1211elrab 3396 . . . . . . . 8 (𝑦 ∈ {𝑥 ∈ ℕ ∣ 𝜑} ↔ (𝑦 ∈ ℕ ∧ 𝜒))
13 nnind.3 . . . . . . . . 9 (𝑥 = (𝑦 + 1) → (𝜑𝜃))
1413elrab 3396 . . . . . . . 8 ((𝑦 + 1) ∈ {𝑥 ∈ ℕ ∣ 𝜑} ↔ ((𝑦 + 1) ∈ ℕ ∧ 𝜃))
1510, 12, 143imtr4g 285 . . . . . . 7 (𝑦 ∈ ℕ → (𝑦 ∈ {𝑥 ∈ ℕ ∣ 𝜑} → (𝑦 + 1) ∈ {𝑥 ∈ ℕ ∣ 𝜑}))
166, 15mpcom 38 . . . . . 6 (𝑦 ∈ {𝑥 ∈ ℕ ∣ 𝜑} → (𝑦 + 1) ∈ {𝑥 ∈ ℕ ∣ 𝜑})
1716rgen 2951 . . . . 5 𝑦 ∈ {𝑥 ∈ ℕ ∣ 𝜑} (𝑦 + 1) ∈ {𝑥 ∈ ℕ ∣ 𝜑}
18 peano5nni 11061 . . . . 5 ((1 ∈ {𝑥 ∈ ℕ ∣ 𝜑} ∧ ∀𝑦 ∈ {𝑥 ∈ ℕ ∣ 𝜑} (𝑦 + 1) ∈ {𝑥 ∈ ℕ ∣ 𝜑}) → ℕ ⊆ {𝑥 ∈ ℕ ∣ 𝜑})
195, 17, 18mp2an 708 . . . 4 ℕ ⊆ {𝑥 ∈ ℕ ∣ 𝜑}
2019sseli 3632 . . 3 (𝐴 ∈ ℕ → 𝐴 ∈ {𝑥 ∈ ℕ ∣ 𝜑})
21 nnind.4 . . . 4 (𝑥 = 𝐴 → (𝜑𝜏))
2221elrab 3396 . . 3 (𝐴 ∈ {𝑥 ∈ ℕ ∣ 𝜑} ↔ (𝐴 ∈ ℕ ∧ 𝜏))
2320, 22sylib 208 . 2 (𝐴 ∈ ℕ → (𝐴 ∈ ℕ ∧ 𝜏))
2423simprd 478 1 (𝐴 ∈ ℕ → 𝜏)
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 196   ∧ wa 383   = wceq 1523   ∈ wcel 2030  ∀wral 2941  {crab 2945   ⊆ wss 3607  (class class class)co 6690  1c1 9975   + caddc 9977  ℕcn 11058 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1762  ax-4 1777  ax-5 1879  ax-6 1945  ax-7 1981  ax-8 2032  ax-9 2039  ax-10 2059  ax-11 2074  ax-12 2087  ax-13 2282  ax-ext 2631  ax-sep 4814  ax-nul 4822  ax-pow 4873  ax-pr 4936  ax-un 6991  ax-1cn 10032 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-3or 1055  df-3an 1056  df-tru 1526  df-ex 1745  df-nf 1750  df-sb 1938  df-eu 2502  df-mo 2503  df-clab 2638  df-cleq 2644  df-clel 2647  df-nfc 2782  df-ne 2824  df-ral 2946  df-rex 2947  df-reu 2948  df-rab 2950  df-v 3233  df-sbc 3469  df-csb 3567  df-dif 3610  df-un 3612  df-in 3614  df-ss 3621  df-pss 3623  df-nul 3949  df-if 4120  df-pw 4193  df-sn 4211  df-pr 4213  df-tp 4215  df-op 4217  df-uni 4469  df-iun 4554  df-br 4686  df-opab 4746  df-mpt 4763  df-tr 4786  df-id 5053  df-eprel 5058  df-po 5064  df-so 5065  df-fr 5102  df-we 5104  df-xp 5149  df-rel 5150  df-cnv 5151  df-co 5152  df-dm 5153  df-rn 5154  df-res 5155  df-ima 5156  df-pred 5718  df-ord 5764  df-on 5765  df-lim 5766  df-suc 5767  df-iota 5889  df-fun 5928  df-fn 5929  df-f 5930  df-f1 5931  df-fo 5932  df-f1o 5933  df-fv 5934  df-ov 6693  df-om 7108  df-wrecs 7452  df-recs 7513  df-rdg 7551  df-nn 11059 This theorem is referenced by:  nnindALT  11077  nn1m1nn  11078  nnaddcl  11080  nnmulcl  11081  nnge1  11084  nnsub  11097  nneo  11499  peano5uzi  11504  nn0ind-raph  11515  ser1const  12897  expcllem  12911  expeq0  12930  seqcoll  13286  relexpsucnnl  13816  relexpcnv  13819  relexprelg  13822  relexpnndm  13825  relexpaddnn  13835  climcndslem2  14626  sqrt2irr  15023  gcdmultiple  15316  rplpwr  15323  prmind2  15445  prmdvdsexp  15474  eulerthlem2  15534  pcmpt  15643  prmpwdvds  15655  vdwlem10  15741  mulgnnass  17623  mulgnnassOLD  17624  imasdsf1olem  22225  ovolunlem1a  23310  ovolicc2lem3  23333  voliunlem1  23364  volsup  23370  dvexp  23761  plyco  24042  dgrcolem1  24074  vieta1  24112  emcllem6  24772  bposlem5  25058  2sqlem10  25198  dchrisum0flb  25244  iuninc  29505  nnindd  29694  ofldchr  29942  nexple  30199  esumfzf  30259  rrvsum  30644  subfacp1lem6  31293  cvmliftlem10  31402  bcprod  31750  faclimlem1  31755  incsequz  33674  bfplem1  33751  2nn0ind  37827  expmordi  37829  relexpxpnnidm  38312  relexpss1d  38314  iunrelexpmin1  38317  relexpmulnn  38318  trclrelexplem  38320  iunrelexpmin2  38321  relexp0a  38325  cotrcltrcl  38334  trclimalb2  38335  cotrclrcl  38351  inductionexd  38770  fmuldfeq  40133  dvnmptconst  40474  stoweidlem20  40555  wallispilem4  40603  wallispi2lem1  40606  wallispi2lem2  40607  dirkertrigeqlem1  40633  iccelpart  41694  nn0sumshdiglem2  42741
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