Step |
Hyp |
Ref |
Expression |
1 |
|
ispconn.1 |
⊢ 𝑋 = ∪ 𝐽 |
2 |
|
unieq |
⊢ ( 𝑗 = 𝐽 → ∪ 𝑗 = ∪ 𝐽 ) |
3 |
2 1
|
eqtr4di |
⊢ ( 𝑗 = 𝐽 → ∪ 𝑗 = 𝑋 ) |
4 |
|
oveq2 |
⊢ ( 𝑗 = 𝐽 → ( II Cn 𝑗 ) = ( II Cn 𝐽 ) ) |
5 |
4
|
rexeqdv |
⊢ ( 𝑗 = 𝐽 → ( ∃ 𝑓 ∈ ( II Cn 𝑗 ) ( ( 𝑓 ‘ 0 ) = 𝑥 ∧ ( 𝑓 ‘ 1 ) = 𝑦 ) ↔ ∃ 𝑓 ∈ ( II Cn 𝐽 ) ( ( 𝑓 ‘ 0 ) = 𝑥 ∧ ( 𝑓 ‘ 1 ) = 𝑦 ) ) ) |
6 |
3 5
|
raleqbidv |
⊢ ( 𝑗 = 𝐽 → ( ∀ 𝑦 ∈ ∪ 𝑗 ∃ 𝑓 ∈ ( II Cn 𝑗 ) ( ( 𝑓 ‘ 0 ) = 𝑥 ∧ ( 𝑓 ‘ 1 ) = 𝑦 ) ↔ ∀ 𝑦 ∈ 𝑋 ∃ 𝑓 ∈ ( II Cn 𝐽 ) ( ( 𝑓 ‘ 0 ) = 𝑥 ∧ ( 𝑓 ‘ 1 ) = 𝑦 ) ) ) |
7 |
3 6
|
raleqbidv |
⊢ ( 𝑗 = 𝐽 → ( ∀ 𝑥 ∈ ∪ 𝑗 ∀ 𝑦 ∈ ∪ 𝑗 ∃ 𝑓 ∈ ( II Cn 𝑗 ) ( ( 𝑓 ‘ 0 ) = 𝑥 ∧ ( 𝑓 ‘ 1 ) = 𝑦 ) ↔ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∃ 𝑓 ∈ ( II Cn 𝐽 ) ( ( 𝑓 ‘ 0 ) = 𝑥 ∧ ( 𝑓 ‘ 1 ) = 𝑦 ) ) ) |
8 |
|
df-pconn |
⊢ PConn = { 𝑗 ∈ Top ∣ ∀ 𝑥 ∈ ∪ 𝑗 ∀ 𝑦 ∈ ∪ 𝑗 ∃ 𝑓 ∈ ( II Cn 𝑗 ) ( ( 𝑓 ‘ 0 ) = 𝑥 ∧ ( 𝑓 ‘ 1 ) = 𝑦 ) } |
9 |
7 8
|
elrab2 |
⊢ ( 𝐽 ∈ PConn ↔ ( 𝐽 ∈ Top ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∃ 𝑓 ∈ ( II Cn 𝐽 ) ( ( 𝑓 ‘ 0 ) = 𝑥 ∧ ( 𝑓 ‘ 1 ) = 𝑦 ) ) ) |