Description: Principle of identity. Theorem *2.08 of WhiteheadRussell p. 101. Copy of id with a different proof. (Contributed by Wolf Lammen, 17-Dec-2018) (New usage is discouraged.) (Proof modification is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | wl-luk-id | |- ( ph -> ph ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ax-luk3 | |- ( ph -> ( -. ph -> ph ) ) |
|
| 2 | ax-luk2 | |- ( ( -. ph -> ph ) -> ph ) |
|
| 3 | 1 2 | wl-luk-syl | |- ( ph -> ph ) |