Description: A <-> identity. (Contributed by Anthony Hart, 22-Oct-2010) (Proof shortened by Andrew Salmon, 13-May-2011) (Proof shortened by Wolf Lammen, 10-Jul-2020)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | falbitru | |- ( ( F. <-> T. ) <-> F. ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | tbtru | |- ( F. <-> ( F. <-> T. ) ) |
|
| 2 | 1 | bicomi | |- ( ( F. <-> T. ) <-> F. ) |