Description: Obsolete version of necon3ai as of 28-Oct-2024. (Contributed by NM, 23-May-2007) (Proof shortened by Andrew Salmon, 25-May-2011) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | necon3ai.1 | |- ( ph -> A = B ) |
|
| Assertion | necon3aiOLD | |- ( A =/= B -> -. ph ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | necon3ai.1 | |- ( ph -> A = B ) |
|
| 2 | nne | |- ( -. A =/= B <-> A = B ) |
|
| 3 | 1 2 | sylibr | |- ( ph -> -. A =/= B ) |
| 4 | 3 | con2i | |- ( A =/= B -> -. ph ) |