| Step | Hyp | Ref
| Expression |
| 1 | | mapvalg 8876 |
. . 3
⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → (𝐴 ↑m 𝐵) = {𝑔 ∣ 𝑔:𝐵⟶𝐴}) |
| 2 | 1 | eleq2d 2827 |
. 2
⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → (𝐶 ∈ (𝐴 ↑m 𝐵) ↔ 𝐶 ∈ {𝑔 ∣ 𝑔:𝐵⟶𝐴})) |
| 3 | | fex2 7958 |
. . . . 5
⊢ ((𝐶:𝐵⟶𝐴 ∧ 𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → 𝐶 ∈ V) |
| 4 | 3 | 3com13 1125 |
. . . 4
⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊 ∧ 𝐶:𝐵⟶𝐴) → 𝐶 ∈ V) |
| 5 | 4 | 3expia 1122 |
. . 3
⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → (𝐶:𝐵⟶𝐴 → 𝐶 ∈ V)) |
| 6 | | feq1 6716 |
. . . 4
⊢ (𝑔 = 𝐶 → (𝑔:𝐵⟶𝐴 ↔ 𝐶:𝐵⟶𝐴)) |
| 7 | 6 | elab3g 3685 |
. . 3
⊢ ((𝐶:𝐵⟶𝐴 → 𝐶 ∈ V) → (𝐶 ∈ {𝑔 ∣ 𝑔:𝐵⟶𝐴} ↔ 𝐶:𝐵⟶𝐴)) |
| 8 | 5, 7 | syl 17 |
. 2
⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → (𝐶 ∈ {𝑔 ∣ 𝑔:𝐵⟶𝐴} ↔ 𝐶:𝐵⟶𝐴)) |
| 9 | 2, 8 | bitrd 279 |
1
⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → (𝐶 ∈ (𝐴 ↑m 𝐵) ↔ 𝐶:𝐵⟶𝐴)) |