USE_THEN : string -> thm_tactic -> tactic

- SYNOPSIS
- Apply a theorem tactic to named assumption.
- DESCRIPTION
- The tactic USE_THEN "name" ttac applies the theorem-tactic ttac to the assumption labelled name (or the first in the list if there is more than one).
- FAILURE CONDITIONS
- Fails if there is no assumption of that name or if the theorem-tactic fails when applied to it.
- EXAMPLE
- See LABEL_TAC for an extended example.
- USES
- Using an assumption identified by name.
- SEE ALSO
- ASSUME, FIND_ASSUM, HYP, LABEL_TAC, REMOVE_THEN.