![]() |
Mathbox for BJ |
< Previous
Next >
Nearby theorems |
|
Mirrors > Home > MPE Home > Th. List > Mathboxes > bj-elsn0 | Structured version Visualization version GIF version |
Description: If the intersection of two classes is a set, then these classes are equal if and only if one is an element of the singleton formed on the other. Stronger form of elsng 4641 and elsn2g 4665 (which could be proved from it). (Contributed by BJ, 20-Jan-2024.) |
Ref | Expression |
---|---|
bj-elsn0 | ⊢ ((𝐴 ∩ 𝐵) ∈ 𝑉 → (𝐴 ∈ {𝐵} ↔ 𝐴 = 𝐵)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | elsni 4644 | . 2 ⊢ (𝐴 ∈ {𝐵} → 𝐴 = 𝐵) | |
2 | bj-inexeqex 36338 | . . . . 5 ⊢ (((𝐴 ∩ 𝐵) ∈ 𝑉 ∧ 𝐴 = 𝐵) → (𝐴 ∈ V ∧ 𝐵 ∈ V)) | |
3 | simpl 481 | . . . . 5 ⊢ ((𝐴 ∈ V ∧ 𝐵 ∈ V) → 𝐴 ∈ V) | |
4 | elsng 4641 | . . . . . 6 ⊢ (𝐴 ∈ V → (𝐴 ∈ {𝐵} ↔ 𝐴 = 𝐵)) | |
5 | 4 | biimprd 247 | . . . . 5 ⊢ (𝐴 ∈ V → (𝐴 = 𝐵 → 𝐴 ∈ {𝐵})) |
6 | 2, 3, 5 | 3syl 18 | . . . 4 ⊢ (((𝐴 ∩ 𝐵) ∈ 𝑉 ∧ 𝐴 = 𝐵) → (𝐴 = 𝐵 → 𝐴 ∈ {𝐵})) |
7 | 6 | ex 411 | . . 3 ⊢ ((𝐴 ∩ 𝐵) ∈ 𝑉 → (𝐴 = 𝐵 → (𝐴 = 𝐵 → 𝐴 ∈ {𝐵}))) |
8 | 7 | pm2.43d 53 | . 2 ⊢ ((𝐴 ∩ 𝐵) ∈ 𝑉 → (𝐴 = 𝐵 → 𝐴 ∈ {𝐵})) |
9 | 1, 8 | impbid2 225 | 1 ⊢ ((𝐴 ∩ 𝐵) ∈ 𝑉 → (𝐴 ∈ {𝐵} ↔ 𝐴 = 𝐵)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 205 ∧ wa 394 = wceq 1539 ∈ wcel 2104 Vcvv 3472 ∩ cin 3946 {csn 4627 |
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-tru 1542 df-ex 1780 df-sb 2066 df-clab 2708 df-cleq 2722 df-clel 2808 df-rab 3431 df-v 3474 df-in 3954 df-ss 3964 df-sn 4628 |
This theorem is referenced by: (None) |
Copyright terms: Public domain | W3C validator |