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Mirrors > Home > ILE Home > Th. List > eubidh | GIF version |
Description: Formula-building rule for uniqueness quantifier (deduction rule). (Contributed by NM, 9-Jul-1994.) |
Ref | Expression |
---|---|
eubidh.1 | ⊢ (𝜑 → ∀𝑥𝜑) |
eubidh.2 | ⊢ (𝜑 → (𝜓 ↔ 𝜒)) |
Ref | Expression |
---|---|
eubidh | ⊢ (𝜑 → (∃!𝑥𝜓 ↔ ∃!𝑥𝜒)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eubidh.1 | . . . 4 ⊢ (𝜑 → ∀𝑥𝜑) | |
2 | eubidh.2 | . . . . 5 ⊢ (𝜑 → (𝜓 ↔ 𝜒)) | |
3 | 2 | bibi1d 231 | . . . 4 ⊢ (𝜑 → ((𝜓 ↔ 𝑥 = 𝑦) ↔ (𝜒 ↔ 𝑥 = 𝑦))) |
4 | 1, 3 | albidh 1409 | . . 3 ⊢ (𝜑 → (∀𝑥(𝜓 ↔ 𝑥 = 𝑦) ↔ ∀𝑥(𝜒 ↔ 𝑥 = 𝑦))) |
5 | 4 | exbidv 1746 | . 2 ⊢ (𝜑 → (∃𝑦∀𝑥(𝜓 ↔ 𝑥 = 𝑦) ↔ ∃𝑦∀𝑥(𝜒 ↔ 𝑥 = 𝑦))) |
6 | df-eu 1944 | . 2 ⊢ (∃!𝑥𝜓 ↔ ∃𝑦∀𝑥(𝜓 ↔ 𝑥 = 𝑦)) | |
7 | df-eu 1944 | . 2 ⊢ (∃!𝑥𝜒 ↔ ∃𝑦∀𝑥(𝜒 ↔ 𝑥 = 𝑦)) | |
8 | 5, 6, 7 | 3bitr4g 221 | 1 ⊢ (𝜑 → (∃!𝑥𝜓 ↔ ∃!𝑥𝜒)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ↔ wb 103 ∀wal 1282 ∃wex 1421 ∃!weu 1941 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-5 1376 ax-gen 1378 ax-ie1 1422 ax-ie2 1423 ax-4 1440 ax-17 1459 ax-ial 1467 |
This theorem depends on definitions: df-bi 115 df-eu 1944 |
This theorem is referenced by: euor 1967 mobidh 1975 euan 1997 euor2 1999 eupickbi 2023 |
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