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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 4308 | . 2 ⊢ (Ord 𝐵 → Tr 𝐵) | |
2 | trss 4043 | . . . . 5 ⊢ (Tr 𝐵 → (𝐴 ∈ 𝐵 → 𝐴 ⊆ 𝐵)) | |
3 | snssi 3672 | . . . . . 6 ⊢ (𝐴 ∈ 𝐵 → {𝐴} ⊆ 𝐵) | |
4 | 3 | a1i 9 | . . . . 5 ⊢ (Tr 𝐵 → (𝐴 ∈ 𝐵 → {𝐴} ⊆ 𝐵)) |
5 | 2, 4 | jcad 305 | . . . 4 ⊢ (Tr 𝐵 → (𝐴 ∈ 𝐵 → (𝐴 ⊆ 𝐵 ∧ {𝐴} ⊆ 𝐵))) |
6 | unss 3255 | . . . 4 ⊢ ((𝐴 ⊆ 𝐵 ∧ {𝐴} ⊆ 𝐵) ↔ (𝐴 ∪ {𝐴}) ⊆ 𝐵) | |
7 | 5, 6 | syl6ib 160 | . . 3 ⊢ (Tr 𝐵 → (𝐴 ∈ 𝐵 → (𝐴 ∪ {𝐴}) ⊆ 𝐵)) |
8 | df-suc 4301 | . . . 4 ⊢ suc 𝐴 = (𝐴 ∪ {𝐴}) | |
9 | 8 | sseq1i 3128 | . . 3 ⊢ (suc 𝐴 ⊆ 𝐵 ↔ (𝐴 ∪ {𝐴}) ⊆ 𝐵) |
10 | 7, 9 | syl6ibr 161 | . 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 103 ∈ wcel 1481 ∪ cun 3074 ⊆ wss 3076 {csn 3532 Tr wtr 4034 Ord word 4292 suc csuc 4295 |
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-io 699 ax-5 1424 ax-7 1425 ax-gen 1426 ax-ie1 1470 ax-ie2 1471 ax-8 1483 ax-10 1484 ax-11 1485 ax-i12 1486 ax-bndl 1487 ax-4 1488 ax-17 1507 ax-i9 1511 ax-ial 1515 ax-i5r 1516 ax-ext 2122 |
This theorem depends on definitions: df-bi 116 df-tru 1335 df-nf 1438 df-sb 1737 df-clab 2127 df-cleq 2133 df-clel 2136 df-nfc 2271 df-ral 2422 df-v 2691 df-un 3080 df-in 3082 df-ss 3089 df-sn 3538 df-uni 3745 df-tr 4035 df-iord 4296 df-suc 4301 |
This theorem is referenced by: ordelsuc 4429 tfrlemibfn 6233 tfr1onlembfn 6249 tfrcllembfn 6262 sucinc2 6350 nndomo 6766 prarloclemn 7331 ennnfonelemhom 11964 ennnfonelemrn 11968 |
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