This is an inofficial mirror of http://metamath.tirix.org for personal testing of a visualizer extension only.
Metamath Proof Explorer
Theorem idd
Description: Principle of identity id with antecedent. (Contributed by NM, 26-Nov-1995)
|
|
Ref |
Expression |
|
Assertion |
idd |
⊢ ( 𝜑 → ( 𝜓 → 𝜓 ) ) |
Proof
| Step |
Hyp |
Ref |
Expression |
| 1 |
|
id |
⊢ ( 𝜓 → 𝜓 ) |
| 2 |
1
|
a1i |
⊢ ( 𝜑 → ( 𝜓 → 𝜓 ) ) |