![]() |
Intuitionistic Logic Explorer |
< Previous
Next >
Nearby theorems |
|
Mirrors > Home > ILE Home > Th. List > ordelsuc | GIF version |
Description: A set belongs to an ordinal iff its successor is a subset of the ordinal. Exercise 8 of [TakeutiZaring] p. 42 and its converse. (Contributed by NM, 29-Nov-2003.) |
Ref | Expression |
---|---|
ordelsuc | ⊢ ((𝐴 ∈ 𝐶 ∧ Ord 𝐵) → (𝐴 ∈ 𝐵 ↔ suc 𝐴 ⊆ 𝐵)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ordsucss 4505 | . . 3 ⊢ (Ord 𝐵 → (𝐴 ∈ 𝐵 → suc 𝐴 ⊆ 𝐵)) | |
2 | 1 | adantl 277 | . 2 ⊢ ((𝐴 ∈ 𝐶 ∧ Ord 𝐵) → (𝐴 ∈ 𝐵 → suc 𝐴 ⊆ 𝐵)) |
3 | sucssel 4426 | . . 3 ⊢ (𝐴 ∈ 𝐶 → (suc 𝐴 ⊆ 𝐵 → 𝐴 ∈ 𝐵)) | |
4 | 3 | adantr 276 | . 2 ⊢ ((𝐴 ∈ 𝐶 ∧ Ord 𝐵) → (suc 𝐴 ⊆ 𝐵 → 𝐴 ∈ 𝐵)) |
5 | 2, 4 | impbid 129 | 1 ⊢ ((𝐴 ∈ 𝐶 ∧ Ord 𝐵) → (𝐴 ∈ 𝐵 ↔ suc 𝐴 ⊆ 𝐵)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 104 ↔ wb 105 ∈ wcel 2148 ⊆ wss 3131 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: onsucssi 4507 onsucmin 4508 onsucelsucr 4509 onsucsssucr 4510 onsucsssucexmid 4528 frecsuclem 6410 ordgt0ge1 6439 nnsucsssuc 6496 ennnfonelemk 12404 nninfsellemeq 14925 |
Copyright terms: Public domain | W3C validator |