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Mirrors > Home > MPE Home > Th. List > dftr5 | Structured version Visualization version GIF version |
Description: An alternate way of defining a transitive class. Definition 1.1 of [Schloeder] p. 1. (Contributed by NM, 20-Mar-2004.) Avoid ax-11 2147. (Revised by BTernaryTau, 28-Dec-2024.) |
Ref | Expression |
---|---|
dftr5 | ⊢ (Tr 𝐴 ↔ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝑥 𝑦 ∈ 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | impexp 450 | . . . . 5 ⊢ (((𝑦 ∈ 𝑥 ∧ 𝑥 ∈ 𝐴) → 𝑦 ∈ 𝐴) ↔ (𝑦 ∈ 𝑥 → (𝑥 ∈ 𝐴 → 𝑦 ∈ 𝐴))) | |
2 | 1 | albii 1814 | . . . 4 ⊢ (∀𝑦((𝑦 ∈ 𝑥 ∧ 𝑥 ∈ 𝐴) → 𝑦 ∈ 𝐴) ↔ ∀𝑦(𝑦 ∈ 𝑥 → (𝑥 ∈ 𝐴 → 𝑦 ∈ 𝐴))) |
3 | df-ral 3058 | . . . 4 ⊢ (∀𝑦 ∈ 𝑥 (𝑥 ∈ 𝐴 → 𝑦 ∈ 𝐴) ↔ ∀𝑦(𝑦 ∈ 𝑥 → (𝑥 ∈ 𝐴 → 𝑦 ∈ 𝐴))) | |
4 | r19.21v 3175 | . . . 4 ⊢ (∀𝑦 ∈ 𝑥 (𝑥 ∈ 𝐴 → 𝑦 ∈ 𝐴) ↔ (𝑥 ∈ 𝐴 → ∀𝑦 ∈ 𝑥 𝑦 ∈ 𝐴)) | |
5 | 2, 3, 4 | 3bitr2i 299 | . . 3 ⊢ (∀𝑦((𝑦 ∈ 𝑥 ∧ 𝑥 ∈ 𝐴) → 𝑦 ∈ 𝐴) ↔ (𝑥 ∈ 𝐴 → ∀𝑦 ∈ 𝑥 𝑦 ∈ 𝐴)) |
6 | 5 | albii 1814 | . 2 ⊢ (∀𝑥∀𝑦((𝑦 ∈ 𝑥 ∧ 𝑥 ∈ 𝐴) → 𝑦 ∈ 𝐴) ↔ ∀𝑥(𝑥 ∈ 𝐴 → ∀𝑦 ∈ 𝑥 𝑦 ∈ 𝐴)) |
7 | dftr2c 5263 | . 2 ⊢ (Tr 𝐴 ↔ ∀𝑥∀𝑦((𝑦 ∈ 𝑥 ∧ 𝑥 ∈ 𝐴) → 𝑦 ∈ 𝐴)) | |
8 | df-ral 3058 | . 2 ⊢ (∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝑥 𝑦 ∈ 𝐴 ↔ ∀𝑥(𝑥 ∈ 𝐴 → ∀𝑦 ∈ 𝑥 𝑦 ∈ 𝐴)) | |
9 | 6, 7, 8 | 3bitr4i 303 | 1 ⊢ (Tr 𝐴 ↔ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝑥 𝑦 ∈ 𝐴) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 205 ∧ wa 395 ∀wal 1532 ∈ wcel 2099 ∀wral 3057 Tr wtr 5260 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1790 ax-4 1804 ax-5 1906 ax-6 1964 ax-7 2004 ax-8 2101 ax-9 2109 ax-ext 2699 |
This theorem depends on definitions: df-bi 206 df-an 396 df-tru 1537 df-ex 1775 df-sb 2061 df-clab 2706 df-cleq 2720 df-clel 2806 df-ral 3058 df-v 3472 df-in 3952 df-ss 3962 df-uni 4905 df-tr 5261 |
This theorem is referenced by: dftr3 5266 smobeth 10604 oaun3lem1 42794 |
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