Detailed syntax breakdown of Definition df-altxp
Step | Hyp | Ref
| Expression |
1 | | cA |
. . 3
class 𝐴 |
2 | | cB |
. . 3
class 𝐵 |
3 | 1, 2 | caltxp 34238 |
. 2
class (𝐴 ×× 𝐵) |
4 | | vz |
. . . . . . 7
setvar 𝑧 |
5 | 4 | cv 1540 |
. . . . . 6
class 𝑧 |
6 | | vx |
. . . . . . . 8
setvar 𝑥 |
7 | 6 | cv 1540 |
. . . . . . 7
class 𝑥 |
8 | | vy |
. . . . . . . 8
setvar 𝑦 |
9 | 8 | cv 1540 |
. . . . . . 7
class 𝑦 |
10 | 7, 9 | caltop 34237 |
. . . . . 6
class
⟪𝑥, 𝑦⟫ |
11 | 5, 10 | wceq 1541 |
. . . . 5
wff 𝑧 = ⟪𝑥, 𝑦⟫ |
12 | 11, 8, 2 | wrex 3066 |
. . . 4
wff
∃𝑦 ∈
𝐵 𝑧 = ⟪𝑥, 𝑦⟫ |
13 | 12, 6, 1 | wrex 3066 |
. . 3
wff
∃𝑥 ∈
𝐴 ∃𝑦 ∈ 𝐵 𝑧 = ⟪𝑥, 𝑦⟫ |
14 | 13, 4 | cab 2716 |
. 2
class {𝑧 ∣ ∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝑧 = ⟪𝑥, 𝑦⟫} |
15 | 3, 14 | wceq 1541 |
1
wff (𝐴 ×× 𝐵) = {𝑧 ∣ ∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝑧 = ⟪𝑥, 𝑦⟫} |