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Mirrors > Home > MPE Home > Th. List > df-fi | Structured version Visualization version GIF version |
Description: Function whose value is the class of finite intersections of the elements of the argument. Note that the empty intersection being the universal class, hence a proper class, it cannot be an element of that class. Therefore, the function value is the class of nonempty finite intersections of elements of the argument (see elfi2 9406). (Contributed by FL, 27-Apr-2008.) |
Ref | Expression |
---|---|
df-fi | ⊢ fi = (𝑥 ∈ V ↦ {𝑧 ∣ ∃𝑦 ∈ (𝒫 𝑥 ∩ Fin)𝑧 = ∩ 𝑦}) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | cfi 9402 | . 2 class fi | |
2 | vx | . . 3 setvar 𝑥 | |
3 | cvv 3466 | . . 3 class V | |
4 | vz | . . . . . . 7 setvar 𝑧 | |
5 | 4 | cv 1532 | . . . . . 6 class 𝑧 |
6 | vy | . . . . . . . 8 setvar 𝑦 | |
7 | 6 | cv 1532 | . . . . . . 7 class 𝑦 |
8 | 7 | cint 4941 | . . . . . 6 class ∩ 𝑦 |
9 | 5, 8 | wceq 1533 | . . . . 5 wff 𝑧 = ∩ 𝑦 |
10 | 2 | cv 1532 | . . . . . . 7 class 𝑥 |
11 | 10 | cpw 4595 | . . . . . 6 class 𝒫 𝑥 |
12 | cfn 8936 | . . . . . 6 class Fin | |
13 | 11, 12 | cin 3940 | . . . . 5 class (𝒫 𝑥 ∩ Fin) |
14 | 9, 6, 13 | wrex 3062 | . . . 4 wff ∃𝑦 ∈ (𝒫 𝑥 ∩ Fin)𝑧 = ∩ 𝑦 |
15 | 14, 4 | cab 2701 | . . 3 class {𝑧 ∣ ∃𝑦 ∈ (𝒫 𝑥 ∩ Fin)𝑧 = ∩ 𝑦} |
16 | 2, 3, 15 | cmpt 5222 | . 2 class (𝑥 ∈ V ↦ {𝑧 ∣ ∃𝑦 ∈ (𝒫 𝑥 ∩ Fin)𝑧 = ∩ 𝑦}) |
17 | 1, 16 | wceq 1533 | 1 wff fi = (𝑥 ∈ V ↦ {𝑧 ∣ ∃𝑦 ∈ (𝒫 𝑥 ∩ Fin)𝑧 = ∩ 𝑦}) |
Colors of variables: wff setvar class |
This definition is referenced by: fival 9404 |
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