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Mirrors > Home > ILE Home > Th. List > nnsseleq | GIF version |
Description: For natural numbers, inclusion is equivalent to membership or equality. (Contributed by Jim Kingdon, 16-Sep-2021.) |
Ref | Expression |
---|---|
nnsseleq | ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 ↔ (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nntri1 6510 | . . 3 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 ↔ ¬ 𝐵 ∈ 𝐴)) | |
2 | nntri3or 6507 | . . . . . 6 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴)) | |
3 | df-3or 980 | . . . . . 6 ⊢ ((𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴) ↔ ((𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵) ∨ 𝐵 ∈ 𝐴)) | |
4 | 2, 3 | sylib 122 | . . . . 5 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → ((𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵) ∨ 𝐵 ∈ 𝐴)) |
5 | 4 | orcomd 730 | . . . 4 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐵 ∈ 𝐴 ∨ (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵))) |
6 | 5 | ord 725 | . . 3 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (¬ 𝐵 ∈ 𝐴 → (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵))) |
7 | 1, 6 | sylbid 150 | . 2 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 → (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵))) |
8 | nnord 4623 | . . . . 5 ⊢ (𝐵 ∈ ω → Ord 𝐵) | |
9 | 8 | adantl 277 | . . . 4 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → Ord 𝐵) |
10 | ordelss 4391 | . . . . 5 ⊢ ((Ord 𝐵 ∧ 𝐴 ∈ 𝐵) → 𝐴 ⊆ 𝐵) | |
11 | 10 | ex 115 | . . . 4 ⊢ (Ord 𝐵 → (𝐴 ∈ 𝐵 → 𝐴 ⊆ 𝐵)) |
12 | 9, 11 | syl 14 | . . 3 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ∈ 𝐵 → 𝐴 ⊆ 𝐵)) |
13 | eqimss 3221 | . . . 4 ⊢ (𝐴 = 𝐵 → 𝐴 ⊆ 𝐵) | |
14 | 13 | a1i 9 | . . 3 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 = 𝐵 → 𝐴 ⊆ 𝐵)) |
15 | 12, 14 | jaod 718 | . 2 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → ((𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵) → 𝐴 ⊆ 𝐵)) |
16 | 7, 15 | impbid 129 | 1 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 ↔ (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵))) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 ∧ wa 104 ↔ wb 105 ∨ wo 709 ∨ w3o 978 = wceq 1363 ∈ wcel 2158 ⊆ wss 3141 Ord word 4374 ωcom 4601 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 615 ax-in2 616 ax-io 710 ax-5 1457 ax-7 1458 ax-gen 1459 ax-ie1 1503 ax-ie2 1504 ax-8 1514 ax-10 1515 ax-11 1516 ax-i12 1517 ax-bndl 1519 ax-4 1520 ax-17 1536 ax-i9 1540 ax-ial 1544 ax-i5r 1545 ax-13 2160 ax-14 2161 ax-ext 2169 ax-sep 4133 ax-nul 4141 ax-pow 4186 ax-pr 4221 ax-un 4445 ax-setind 4548 ax-iinf 4599 |
This theorem depends on definitions: df-bi 117 df-3or 980 df-3an 981 df-tru 1366 df-nf 1471 df-sb 1773 df-clab 2174 df-cleq 2180 df-clel 2183 df-nfc 2318 df-ne 2358 df-ral 2470 df-rex 2471 df-v 2751 df-dif 3143 df-un 3145 df-in 3147 df-ss 3154 df-nul 3435 df-pw 3589 df-sn 3610 df-pr 3611 df-uni 3822 df-int 3857 df-tr 4114 df-iord 4378 df-on 4380 df-suc 4383 df-iom 4602 |
This theorem is referenced by: nnsssuc 6516 frec2uzled 10442 |
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