Description: Strong transfinite recursion defines a function on ordinals. (Contributed by Stefan O'Rear, 18-Jan-2015)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | recsfnon | |- recs ( F ) Fn On | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | eqid | |- recs ( F ) = recs ( F ) | |
| 2 | 1 | tfr1 | |- recs ( F ) Fn On |