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Mirrors > Home > MPE Home > Th. List > Mathboxes > fipjust | Structured version Visualization version GIF version |
Description: A definition of the finite intersection property of a class based on closure under pairwise intersection of its elements is independent of the dummy variables. (Contributed by RP, 1-Jan-2020.) |
Ref | Expression |
---|---|
fipjust | ⊢ (∀𝑢 ∈ 𝐴 ∀𝑣 ∈ 𝐴 (𝑢 ∩ 𝑣) ∈ 𝐴 ↔ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥 ∩ 𝑦) ∈ 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ineq1 4131 | . . 3 ⊢ (𝑢 = 𝑥 → (𝑢 ∩ 𝑣) = (𝑥 ∩ 𝑣)) | |
2 | 1 | eleq1d 2874 | . 2 ⊢ (𝑢 = 𝑥 → ((𝑢 ∩ 𝑣) ∈ 𝐴 ↔ (𝑥 ∩ 𝑣) ∈ 𝐴)) |
3 | ineq2 4133 | . . 3 ⊢ (𝑣 = 𝑦 → (𝑥 ∩ 𝑣) = (𝑥 ∩ 𝑦)) | |
4 | 3 | eleq1d 2874 | . 2 ⊢ (𝑣 = 𝑦 → ((𝑥 ∩ 𝑣) ∈ 𝐴 ↔ (𝑥 ∩ 𝑦) ∈ 𝐴)) |
5 | 2, 4 | cbvral2vw 3408 | 1 ⊢ (∀𝑢 ∈ 𝐴 ∀𝑣 ∈ 𝐴 (𝑢 ∩ 𝑣) ∈ 𝐴 ↔ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥 ∩ 𝑦) ∈ 𝐴) |
Colors of variables: wff setvar class |
Syntax hints: ↔ wb 209 ∈ wcel 2111 ∀wral 3106 ∩ cin 3880 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2113 ax-9 2121 ax-ext 2770 |
This theorem depends on definitions: df-bi 210 df-an 400 df-tru 1541 df-ex 1782 df-sb 2070 df-clab 2777 df-cleq 2791 df-clel 2870 df-ral 3111 df-rab 3115 df-in 3888 |
This theorem is referenced by: (None) |
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