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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 6192 | . . 3 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 ↔ ¬ 𝐵 ∈ 𝐴)) | |
2 | nntri3or 6189 | . . . . . 6 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴)) | |
3 | df-3or 923 | . . . . . 6 ⊢ ((𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴) ↔ ((𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵) ∨ 𝐵 ∈ 𝐴)) | |
4 | 2, 3 | sylib 120 | . . . . 5 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → ((𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵) ∨ 𝐵 ∈ 𝐴)) |
5 | 4 | orcomd 681 | . . . 4 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐵 ∈ 𝐴 ∨ (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵))) |
6 | 5 | ord 676 | . . 3 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (¬ 𝐵 ∈ 𝐴 → (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵))) |
7 | 1, 6 | sylbid 148 | . 2 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 → (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵))) |
8 | nnord 4392 | . . . . 5 ⊢ (𝐵 ∈ ω → Ord 𝐵) | |
9 | 8 | adantl 271 | . . . 4 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → Ord 𝐵) |
10 | ordelss 4173 | . . . . 5 ⊢ ((Ord 𝐵 ∧ 𝐴 ∈ 𝐵) → 𝐴 ⊆ 𝐵) | |
11 | 10 | ex 113 | . . . 4 ⊢ (Ord 𝐵 → (𝐴 ∈ 𝐵 → 𝐴 ⊆ 𝐵)) |
12 | 9, 11 | syl 14 | . . 3 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ∈ 𝐵 → 𝐴 ⊆ 𝐵)) |
13 | eqimss 3064 | . . . 4 ⊢ (𝐴 = 𝐵 → 𝐴 ⊆ 𝐵) | |
14 | 13 | a1i 9 | . . 3 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 = 𝐵 → 𝐴 ⊆ 𝐵)) |
15 | 12, 14 | jaod 670 | . 2 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → ((𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵) → 𝐴 ⊆ 𝐵)) |
16 | 7, 15 | impbid 127 | 1 ⊢ ((𝐴 ∈ ω ∧ 𝐵 ∈ ω) → (𝐴 ⊆ 𝐵 ↔ (𝐴 ∈ 𝐵 ∨ 𝐴 = 𝐵))) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 ∧ wa 102 ↔ wb 103 ∨ wo 662 ∨ w3o 921 = wceq 1287 ∈ wcel 1436 ⊆ wss 2986 Ord word 4156 ωcom 4371 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-in1 577 ax-in2 578 ax-io 663 ax-5 1379 ax-7 1380 ax-gen 1381 ax-ie1 1425 ax-ie2 1426 ax-8 1438 ax-10 1439 ax-11 1440 ax-i12 1441 ax-bndl 1442 ax-4 1443 ax-13 1447 ax-14 1448 ax-17 1462 ax-i9 1466 ax-ial 1470 ax-i5r 1471 ax-ext 2067 ax-sep 3925 ax-nul 3933 ax-pow 3977 ax-pr 4003 ax-un 4227 ax-setind 4319 ax-iinf 4369 |
This theorem depends on definitions: df-bi 115 df-3or 923 df-3an 924 df-tru 1290 df-nf 1393 df-sb 1690 df-clab 2072 df-cleq 2078 df-clel 2081 df-nfc 2214 df-ne 2252 df-ral 2360 df-rex 2361 df-v 2616 df-dif 2988 df-un 2990 df-in 2992 df-ss 2999 df-nul 3273 df-pw 3411 df-sn 3431 df-pr 3432 df-uni 3631 df-int 3666 df-tr 3905 df-iord 4160 df-on 4162 df-suc 4165 df-iom 4372 |
This theorem is referenced by: frec2uzled 9739 |
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