Description: The first of three axioms in the Tarski-Bernays axiom system. (Contributed by Anthony Hart, 16-Aug-2011) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | tb-ax1 | |- ( ( ph -> ps ) -> ( ( ps -> ch ) -> ( ph -> ch ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | imim1 | |- ( ( ph -> ps ) -> ( ( ps -> ch ) -> ( ph -> ch ) ) ) |