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Mirrors > Home > MPE Home > Th. List > eleq2w2 | Structured version Visualization version GIF version |
Description: A weaker version of eleq2 2828 (but stronger than ax-9 2116 and elequ2 2121) that uses ax-12 2175 to avoid ax-8 2108 and df-clel 2814. Compare eleq2w 2823, whose setvars appear where the class variables are in this theorem, and vice versa. (Contributed by BJ, 24-Jun-2019.) Strengthen from setvar variables to class variables. (Revised by WL and SN, 23-Aug-2024.) |
Ref | Expression |
---|---|
eleq2w2 | ⊢ (𝐴 = 𝐵 → (𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfcleq 2728 | . . 3 ⊢ (𝐴 = 𝐵 ↔ ∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵)) | |
2 | 1 | biimpi 216 | . 2 ⊢ (𝐴 = 𝐵 → ∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵)) |
3 | 2 | 19.21bi 2187 | 1 ⊢ (𝐴 = 𝐵 → (𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 206 ∀wal 1535 = wceq 1537 ∈ wcel 2106 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1792 ax-4 1806 ax-5 1908 ax-6 1965 ax-7 2005 ax-9 2116 ax-12 2175 ax-ext 2706 |
This theorem depends on definitions: df-bi 207 df-an 396 df-ex 1777 df-cleq 2727 |
This theorem is referenced by: nfceqdf 2899 drnfc1 2923 drnfc2 2924 fineqvrep 35088 fineqvpow 35089 fineqvac 35090 fvineqsneu 37394 sge0f1o 46338 f1omo 48691 |
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