Description: Restate implication as conditional logic operator. (Contributed by RP, 20-Apr-2020)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | ifpim1 | |- ( ( ph -> ps ) <-> if- ( -. ph , T. , ps ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | tru | |- T. |
|
| 2 | 1 | olci | |- ( -. -. ph \/ T. ) |
| 3 | 2 | biantrur | |- ( ( -. ph \/ ps ) <-> ( ( -. -. ph \/ T. ) /\ ( -. ph \/ ps ) ) ) |
| 4 | imor | |- ( ( ph -> ps ) <-> ( -. ph \/ ps ) ) |
|
| 5 | dfifp4 | |- ( if- ( -. ph , T. , ps ) <-> ( ( -. -. ph \/ T. ) /\ ( -. ph \/ ps ) ) ) |
|
| 6 | 3 4 5 | 3bitr4i | |- ( ( ph -> ps ) <-> if- ( -. ph , T. , ps ) ) |