Abstract: Using Theory Morphisms for Implementing Formal Methods Tools Achim D. Brucker and Burkhart Wolff Tools for a specification language can be implemented directly (by building a special purpose theorem prover) or by a conservative embedding into a typed meta-logic, which allows their safe and logically consistent implementation and the reuse of existing theorem prover engines. For being useful, the conservative extension approach must provide derivations for several thousand ``folklore'' theorems. In this paper, we present an approach for deriving the mass of these theorems mechanically from an existing library of the meta-logic. The approach presupposes a structured theory morphism mapping library datatypes and library functions to new functions of the specification language while uniformly modifying some semantic properties; for example, new functions may have a different treatment of undefinedness compared to old ones.