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Mirrors > Home > MPE Home > Th. List > Mathboxes > bj-sb | Structured version Visualization version GIF version |
Description: A weak variant of sbid2 2514 not requiring ax-13 2374 nor ax-10 2141. On top of Tarski's FOL, one implication requires only ax12v 2176, and the other requires only sp 2180. (Contributed by BJ, 25-May-2021.) |
Ref | Expression |
---|---|
bj-sb | ⊢ (𝜑 ↔ ∀𝑦(𝑦 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝜑))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ax12v 2176 | . . . . 5 ⊢ (𝑥 = 𝑦 → (𝜑 → ∀𝑥(𝑥 = 𝑦 → 𝜑))) | |
2 | 1 | equcoms 2027 | . . . 4 ⊢ (𝑦 = 𝑥 → (𝜑 → ∀𝑥(𝑥 = 𝑦 → 𝜑))) |
3 | 2 | com12 32 | . . 3 ⊢ (𝜑 → (𝑦 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝜑))) |
4 | 3 | alrimiv 1934 | . 2 ⊢ (𝜑 → ∀𝑦(𝑦 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝜑))) |
5 | sp 2180 | . . . . . . 7 ⊢ (∀𝑥(𝑥 = 𝑦 → 𝜑) → (𝑥 = 𝑦 → 𝜑)) | |
6 | 5 | com12 32 | . . . . . 6 ⊢ (𝑥 = 𝑦 → (∀𝑥(𝑥 = 𝑦 → 𝜑) → 𝜑)) |
7 | 6 | equcoms 2027 | . . . . 5 ⊢ (𝑦 = 𝑥 → (∀𝑥(𝑥 = 𝑦 → 𝜑) → 𝜑)) |
8 | 7 | a2i 14 | . . . 4 ⊢ ((𝑦 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝜑)) → (𝑦 = 𝑥 → 𝜑)) |
9 | 8 | alimi 1818 | . . 3 ⊢ (∀𝑦(𝑦 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝜑)) → ∀𝑦(𝑦 = 𝑥 → 𝜑)) |
10 | bj-eqs 34865 | . . 3 ⊢ (𝜑 ↔ ∀𝑦(𝑦 = 𝑥 → 𝜑)) | |
11 | 9, 10 | sylibr 233 | . 2 ⊢ (∀𝑦(𝑦 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝜑)) → 𝜑) |
12 | 4, 11 | impbii 208 | 1 ⊢ (𝜑 ↔ ∀𝑦(𝑦 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝜑))) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 205 ∀wal 1540 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1802 ax-4 1816 ax-5 1917 ax-6 1975 ax-7 2015 ax-12 2175 |
This theorem depends on definitions: df-bi 206 df-an 397 df-ex 1787 |
This theorem is referenced by: (None) |
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