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Mirrors > Home > MPE Home > Th. List > unisucg | Structured version Visualization version GIF version |
Description: A transitive class is equal to the union of its successor, closed form. Combines Theorem 4E of [Enderton] p. 72 and Exercise 6 of [Enderton] p. 73. (Contributed by NM, 30-Aug-1993.) Generalize from unisuc 6442. (Revised by BJ, 28-Dec-2024.) |
Ref | Expression |
---|---|
unisucg | ⊢ (𝐴 ∈ 𝑉 → (Tr 𝐴 ↔ ∪ suc 𝐴 = 𝐴)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ssequn1 4179 | . . 3 ⊢ (∪ 𝐴 ⊆ 𝐴 ↔ (∪ 𝐴 ∪ 𝐴) = 𝐴) | |
2 | 1 | a1i 11 | . 2 ⊢ (𝐴 ∈ 𝑉 → (∪ 𝐴 ⊆ 𝐴 ↔ (∪ 𝐴 ∪ 𝐴) = 𝐴)) |
3 | df-tr 5265 | . . 3 ⊢ (Tr 𝐴 ↔ ∪ 𝐴 ⊆ 𝐴) | |
4 | 3 | a1i 11 | . 2 ⊢ (𝐴 ∈ 𝑉 → (Tr 𝐴 ↔ ∪ 𝐴 ⊆ 𝐴)) |
5 | unisucs 6440 | . . 3 ⊢ (𝐴 ∈ 𝑉 → ∪ suc 𝐴 = (∪ 𝐴 ∪ 𝐴)) | |
6 | 5 | eqeq1d 2732 | . 2 ⊢ (𝐴 ∈ 𝑉 → (∪ suc 𝐴 = 𝐴 ↔ (∪ 𝐴 ∪ 𝐴) = 𝐴)) |
7 | 2, 4, 6 | 3bitr4d 310 | 1 ⊢ (𝐴 ∈ 𝑉 → (Tr 𝐴 ↔ ∪ suc 𝐴 = 𝐴)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 205 = wceq 1539 ∈ wcel 2104 ∪ cun 3945 ⊆ wss 3947 ∪ cuni 4907 Tr wtr 5264 suc csuc 6365 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1795 ax-4 1809 ax-5 1911 ax-6 1969 ax-7 2009 ax-8 2106 ax-9 2114 ax-ext 2701 |
This theorem depends on definitions: df-bi 206 df-an 395 df-or 844 df-tru 1542 df-ex 1780 df-sb 2066 df-clab 2708 df-cleq 2722 df-clel 2808 df-v 3474 df-un 3952 df-in 3954 df-ss 3964 df-sn 4628 df-pr 4630 df-uni 4908 df-tr 5265 df-suc 6369 |
This theorem is referenced by: unisuc 6442 onunisuc 6473 |
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