Description: A symbol within a word over an alphabet belongs to the alphabet. (Contributed by Alexander van der Vekens, 28-Jun-2018)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | wrdsymbcl | |- ( ( W e. Word V /\ I e. ( 0 ..^ ( # ` W ) ) ) -> ( W ` I ) e. V ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | wrdf | |- ( W e. Word V -> W : ( 0 ..^ ( # ` W ) ) --> V ) |
|
| 2 | 1 | ffvelcdmda | |- ( ( W e. Word V /\ I e. ( 0 ..^ ( # ` W ) ) ) -> ( W ` I ) e. V ) |