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Mirrors > Home > ILE Home > Th. List > indstr2 | GIF version |
Description: Strong Mathematical Induction for positive integers (inference schema). The first two hypotheses give us the substitution instances we need; the last two are the basis and the induction step. (Contributed by Paul Chapman, 21-Nov-2012.) |
Ref | Expression |
---|---|
indstr2.1 | ⊢ (𝑥 = 1 → (𝜑 ↔ 𝜒)) |
indstr2.2 | ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) |
indstr2.3 | ⊢ 𝜒 |
indstr2.4 | ⊢ (𝑥 ∈ (ℤ≥‘2) → (∀𝑦 ∈ ℕ (𝑦 < 𝑥 → 𝜓) → 𝜑)) |
Ref | Expression |
---|---|
indstr2 | ⊢ (𝑥 ∈ ℕ → 𝜑) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | indstr2.2 | . 2 ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) | |
2 | elnn1uz2 9537 | . . 3 ⊢ (𝑥 ∈ ℕ ↔ (𝑥 = 1 ∨ 𝑥 ∈ (ℤ≥‘2))) | |
3 | indstr2.3 | . . . . 5 ⊢ 𝜒 | |
4 | nnnlt1 8875 | . . . . . . . . . . 11 ⊢ (𝑦 ∈ ℕ → ¬ 𝑦 < 1) | |
5 | 4 | adantl 275 | . . . . . . . . . 10 ⊢ ((𝑥 = 1 ∧ 𝑦 ∈ ℕ) → ¬ 𝑦 < 1) |
6 | breq2 3981 | . . . . . . . . . . 11 ⊢ (𝑥 = 1 → (𝑦 < 𝑥 ↔ 𝑦 < 1)) | |
7 | 6 | adantr 274 | . . . . . . . . . 10 ⊢ ((𝑥 = 1 ∧ 𝑦 ∈ ℕ) → (𝑦 < 𝑥 ↔ 𝑦 < 1)) |
8 | 5, 7 | mtbird 663 | . . . . . . . . 9 ⊢ ((𝑥 = 1 ∧ 𝑦 ∈ ℕ) → ¬ 𝑦 < 𝑥) |
9 | 8 | pm2.21d 609 | . . . . . . . 8 ⊢ ((𝑥 = 1 ∧ 𝑦 ∈ ℕ) → (𝑦 < 𝑥 → 𝜓)) |
10 | 9 | ralrimiva 2537 | . . . . . . 7 ⊢ (𝑥 = 1 → ∀𝑦 ∈ ℕ (𝑦 < 𝑥 → 𝜓)) |
11 | pm5.5 241 | . . . . . . 7 ⊢ (∀𝑦 ∈ ℕ (𝑦 < 𝑥 → 𝜓) → ((∀𝑦 ∈ ℕ (𝑦 < 𝑥 → 𝜓) → 𝜑) ↔ 𝜑)) | |
12 | 10, 11 | syl 14 | . . . . . 6 ⊢ (𝑥 = 1 → ((∀𝑦 ∈ ℕ (𝑦 < 𝑥 → 𝜓) → 𝜑) ↔ 𝜑)) |
13 | indstr2.1 | . . . . . 6 ⊢ (𝑥 = 1 → (𝜑 ↔ 𝜒)) | |
14 | 12, 13 | bitrd 187 | . . . . 5 ⊢ (𝑥 = 1 → ((∀𝑦 ∈ ℕ (𝑦 < 𝑥 → 𝜓) → 𝜑) ↔ 𝜒)) |
15 | 3, 14 | mpbiri 167 | . . . 4 ⊢ (𝑥 = 1 → (∀𝑦 ∈ ℕ (𝑦 < 𝑥 → 𝜓) → 𝜑)) |
16 | indstr2.4 | . . . 4 ⊢ (𝑥 ∈ (ℤ≥‘2) → (∀𝑦 ∈ ℕ (𝑦 < 𝑥 → 𝜓) → 𝜑)) | |
17 | 15, 16 | jaoi 706 | . . 3 ⊢ ((𝑥 = 1 ∨ 𝑥 ∈ (ℤ≥‘2)) → (∀𝑦 ∈ ℕ (𝑦 < 𝑥 → 𝜓) → 𝜑)) |
18 | 2, 17 | sylbi 120 | . 2 ⊢ (𝑥 ∈ ℕ → (∀𝑦 ∈ ℕ (𝑦 < 𝑥 → 𝜓) → 𝜑)) |
19 | 1, 18 | indstr 9523 | 1 ⊢ (𝑥 ∈ ℕ → 𝜑) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 ∧ wa 103 ↔ wb 104 ∨ wo 698 = wceq 1342 ∈ wcel 2135 ∀wral 2442 class class class wbr 3977 ‘cfv 5183 1c1 7746 < clt 7925 ℕcn 8849 2c2 8900 ℤ≥cuz 9458 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 604 ax-in2 605 ax-io 699 ax-5 1434 ax-7 1435 ax-gen 1436 ax-ie1 1480 ax-ie2 1481 ax-8 1491 ax-10 1492 ax-11 1493 ax-i12 1494 ax-bndl 1496 ax-4 1497 ax-17 1513 ax-i9 1517 ax-ial 1521 ax-i5r 1522 ax-13 2137 ax-14 2138 ax-ext 2146 ax-sep 4095 ax-pow 4148 ax-pr 4182 ax-un 4406 ax-setind 4509 ax-cnex 7836 ax-resscn 7837 ax-1cn 7838 ax-1re 7839 ax-icn 7840 ax-addcl 7841 ax-addrcl 7842 ax-mulcl 7843 ax-addcom 7845 ax-addass 7847 ax-distr 7849 ax-i2m1 7850 ax-0lt1 7851 ax-0id 7853 ax-rnegex 7854 ax-cnre 7856 ax-pre-ltirr 7857 ax-pre-ltwlin 7858 ax-pre-lttrn 7859 ax-pre-ltadd 7861 |
This theorem depends on definitions: df-bi 116 df-dc 825 df-3or 968 df-3an 969 df-tru 1345 df-fal 1348 df-nf 1448 df-sb 1750 df-eu 2016 df-mo 2017 df-clab 2151 df-cleq 2157 df-clel 2160 df-nfc 2295 df-ne 2335 df-nel 2430 df-ral 2447 df-rex 2448 df-reu 2449 df-rab 2451 df-v 2724 df-sbc 2948 df-dif 3114 df-un 3116 df-in 3118 df-ss 3125 df-pw 3556 df-sn 3577 df-pr 3578 df-op 3580 df-uni 3785 df-int 3820 df-br 3978 df-opab 4039 df-mpt 4040 df-id 4266 df-xp 4605 df-rel 4606 df-cnv 4607 df-co 4608 df-dm 4609 df-rn 4610 df-res 4611 df-ima 4612 df-iota 5148 df-fun 5185 df-fn 5186 df-f 5187 df-fv 5191 df-riota 5793 df-ov 5840 df-oprab 5841 df-mpo 5842 df-pnf 7927 df-mnf 7928 df-xr 7929 df-ltxr 7930 df-le 7931 df-sub 8063 df-neg 8064 df-inn 8850 df-2 8908 df-n0 9107 df-z 9184 df-uz 9459 |
This theorem is referenced by: (None) |
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