Proof of Theorem spsbim
| Step | Hyp | Ref
 | Expression | 
| 1 |   | imim2 55 | 
. . . 4
⊢ ((𝜑 → 𝜓) → ((𝑥 = 𝑦 → 𝜑) → (𝑥 = 𝑦 → 𝜓))) | 
| 2 | 1 | sps 1551 | 
. . 3
⊢
(∀𝑥(𝜑 → 𝜓) → ((𝑥 = 𝑦 → 𝜑) → (𝑥 = 𝑦 → 𝜓))) | 
| 3 |   | id 19 | 
. . . . . 6
⊢ ((𝜑 → 𝜓) → (𝜑 → 𝜓)) | 
| 4 | 3 | anim2d 337 | 
. . . . 5
⊢ ((𝜑 → 𝜓) → ((𝑥 = 𝑦 ∧ 𝜑) → (𝑥 = 𝑦 ∧ 𝜓))) | 
| 5 | 4 | alimi 1469 | 
. . . 4
⊢
(∀𝑥(𝜑 → 𝜓) → ∀𝑥((𝑥 = 𝑦 ∧ 𝜑) → (𝑥 = 𝑦 ∧ 𝜓))) | 
| 6 |   | exim 1613 | 
. . . 4
⊢
(∀𝑥((𝑥 = 𝑦 ∧ 𝜑) → (𝑥 = 𝑦 ∧ 𝜓)) → (∃𝑥(𝑥 = 𝑦 ∧ 𝜑) → ∃𝑥(𝑥 = 𝑦 ∧ 𝜓))) | 
| 7 | 5, 6 | syl 14 | 
. . 3
⊢
(∀𝑥(𝜑 → 𝜓) → (∃𝑥(𝑥 = 𝑦 ∧ 𝜑) → ∃𝑥(𝑥 = 𝑦 ∧ 𝜓))) | 
| 8 | 2, 7 | anim12d 335 | 
. 2
⊢
(∀𝑥(𝜑 → 𝜓) → (((𝑥 = 𝑦 → 𝜑) ∧ ∃𝑥(𝑥 = 𝑦 ∧ 𝜑)) → ((𝑥 = 𝑦 → 𝜓) ∧ ∃𝑥(𝑥 = 𝑦 ∧ 𝜓)))) | 
| 9 |   | df-sb 1777 | 
. 2
⊢ ([𝑦 / 𝑥]𝜑 ↔ ((𝑥 = 𝑦 → 𝜑) ∧ ∃𝑥(𝑥 = 𝑦 ∧ 𝜑))) | 
| 10 |   | df-sb 1777 | 
. 2
⊢ ([𝑦 / 𝑥]𝜓 ↔ ((𝑥 = 𝑦 → 𝜓) ∧ ∃𝑥(𝑥 = 𝑦 ∧ 𝜓))) | 
| 11 | 8, 9, 10 | 3imtr4g 205 | 
1
⊢
(∀𝑥(𝜑 → 𝜓) → ([𝑦 / 𝑥]𝜑 → [𝑦 / 𝑥]𝜓)) |