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Mirrors > Home > ILE Home > Th. List > ordsucss | GIF version |
Description: The successor of an element of an ordinal class is a subset of it. (Contributed by NM, 21-Jun-1998.) |
Ref | Expression |
---|---|
ordsucss | ⊢ (Ord 𝐵 → (𝐴 ∈ 𝐵 → suc 𝐴 ⊆ 𝐵)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ordtr 4380 | . 2 ⊢ (Ord 𝐵 → Tr 𝐵) | |
2 | trss 4112 | . . . . 5 ⊢ (Tr 𝐵 → (𝐴 ∈ 𝐵 → 𝐴 ⊆ 𝐵)) | |
3 | snssi 3738 | . . . . . 6 ⊢ (𝐴 ∈ 𝐵 → {𝐴} ⊆ 𝐵) | |
4 | 3 | a1i 9 | . . . . 5 ⊢ (Tr 𝐵 → (𝐴 ∈ 𝐵 → {𝐴} ⊆ 𝐵)) |
5 | 2, 4 | jcad 307 | . . . 4 ⊢ (Tr 𝐵 → (𝐴 ∈ 𝐵 → (𝐴 ⊆ 𝐵 ∧ {𝐴} ⊆ 𝐵))) |
6 | unss 3311 | . . . 4 ⊢ ((𝐴 ⊆ 𝐵 ∧ {𝐴} ⊆ 𝐵) ↔ (𝐴 ∪ {𝐴}) ⊆ 𝐵) | |
7 | 5, 6 | imbitrdi 161 | . . 3 ⊢ (Tr 𝐵 → (𝐴 ∈ 𝐵 → (𝐴 ∪ {𝐴}) ⊆ 𝐵)) |
8 | df-suc 4373 | . . . 4 ⊢ suc 𝐴 = (𝐴 ∪ {𝐴}) | |
9 | 8 | sseq1i 3183 | . . 3 ⊢ (suc 𝐴 ⊆ 𝐵 ↔ (𝐴 ∪ {𝐴}) ⊆ 𝐵) |
10 | 7, 9 | imbitrrdi 162 | . 2 ⊢ (Tr 𝐵 → (𝐴 ∈ 𝐵 → suc 𝐴 ⊆ 𝐵)) |
11 | 1, 10 | syl 14 | 1 ⊢ (Ord 𝐵 → (𝐴 ∈ 𝐵 → suc 𝐴 ⊆ 𝐵)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 104 ∈ wcel 2148 ∪ cun 3129 ⊆ wss 3131 {csn 3594 Tr wtr 4103 Ord word 4364 suc csuc 4367 |
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-io 709 ax-5 1447 ax-7 1448 ax-gen 1449 ax-ie1 1493 ax-ie2 1494 ax-8 1504 ax-10 1505 ax-11 1506 ax-i12 1507 ax-bndl 1509 ax-4 1510 ax-17 1526 ax-i9 1530 ax-ial 1534 ax-i5r 1535 ax-ext 2159 |
This theorem depends on definitions: df-bi 117 df-tru 1356 df-nf 1461 df-sb 1763 df-clab 2164 df-cleq 2170 df-clel 2173 df-nfc 2308 df-ral 2460 df-v 2741 df-un 3135 df-in 3137 df-ss 3144 df-sn 3600 df-uni 3812 df-tr 4104 df-iord 4368 df-suc 4373 |
This theorem is referenced by: ordelsuc 4506 tfrlemibfn 6331 tfr1onlembfn 6347 tfrcllembfn 6360 sucinc2 6449 nndomo 6866 prarloclemn 7500 ennnfonelemhom 12418 ennnfonelemrn 12422 |
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