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| Mirrors > Home > PE Home > Th. List > df-true-D2.4 | |||
| Description: Definition of True, '⊤'. |
| Ref | Expression |
|---|---|
| df-true-D2.4 | ⊢ (⊤ ↔ (∀𝑥 𝑥 = 𝑥 → ∀𝑥 𝑥 = 𝑥)) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | wff-true 153 | . 2 wff ⊤ | |
| 2 | objvar-x | . . . . . 6 objvar 𝑥 | |
| 3 | 2 | term-obj 1 | . . . . 5 term 𝑥 |
| 4 | 3, 3 | wff-equals 6 | . . . 4 wff 𝑥 = 𝑥 |
| 5 | 4, 2 | wff-forall 8 | . . 3 wff ∀𝑥 𝑥 = 𝑥 |
| 6 | 5, 5 | wff-imp 10 | . 2 wff (∀𝑥 𝑥 = 𝑥 → ∀𝑥 𝑥 = 𝑥) |
| 7 | 1, 6 | wff-bi 104 | 1 wff (⊤ ↔ (∀𝑥 𝑥 = 𝑥 → ∀𝑥 𝑥 = 𝑥)) |
| Colors of variables: wff objvar term class |
| This definition is referenced by: true-P2.14 156 |
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