Metamath Proof Explorer


Theorem rniun

Description: The range of an indexed union. (Contributed by Mario Carneiro, 29-May-2015)

Ref Expression
Assertion rniun ran 𝑥𝐴 𝐵 = 𝑥𝐴 ran 𝐵

Proof

Step Hyp Ref Expression
1 rexcom4 ( ∃ 𝑥𝐴𝑦𝑦 , 𝑧 ⟩ ∈ 𝐵 ↔ ∃ 𝑦𝑥𝐴𝑦 , 𝑧 ⟩ ∈ 𝐵 )
2 vex 𝑧 ∈ V
3 2 elrn2 ( 𝑧 ∈ ran 𝐵 ↔ ∃ 𝑦𝑦 , 𝑧 ⟩ ∈ 𝐵 )
4 3 rexbii ( ∃ 𝑥𝐴 𝑧 ∈ ran 𝐵 ↔ ∃ 𝑥𝐴𝑦𝑦 , 𝑧 ⟩ ∈ 𝐵 )
5 eliun ( ⟨ 𝑦 , 𝑧 ⟩ ∈ 𝑥𝐴 𝐵 ↔ ∃ 𝑥𝐴𝑦 , 𝑧 ⟩ ∈ 𝐵 )
6 5 exbii ( ∃ 𝑦𝑦 , 𝑧 ⟩ ∈ 𝑥𝐴 𝐵 ↔ ∃ 𝑦𝑥𝐴𝑦 , 𝑧 ⟩ ∈ 𝐵 )
7 1 4 6 3bitr4ri ( ∃ 𝑦𝑦 , 𝑧 ⟩ ∈ 𝑥𝐴 𝐵 ↔ ∃ 𝑥𝐴 𝑧 ∈ ran 𝐵 )
8 2 elrn2 ( 𝑧 ∈ ran 𝑥𝐴 𝐵 ↔ ∃ 𝑦𝑦 , 𝑧 ⟩ ∈ 𝑥𝐴 𝐵 )
9 eliun ( 𝑧 𝑥𝐴 ran 𝐵 ↔ ∃ 𝑥𝐴 𝑧 ∈ ran 𝐵 )
10 7 8 9 3bitr4i ( 𝑧 ∈ ran 𝑥𝐴 𝐵𝑧 𝑥𝐴 ran 𝐵 )
11 10 eqriv ran 𝑥𝐴 𝐵 = 𝑥𝐴 ran 𝐵