Combining Ws1s and Hol

We investigate the combination of the weak second-order monadic logic of one successor (WS1S) with higher-order logic (HOL). We show how these two logics can be combined, how theorem provers based on them can be safely integrated, and how the result can be used. In particular , we present an embedding of the semantics of WS1S in HOL that provides a basis for coupling the MONA system, a decision procedure for WS1S, with an implementation of HOL in the Isabelle system. Afterwards, we describe methods that reduce problems formalized in HOL to problems in the language of WS1S. We present applications to arithmetic reasoning and proving properties of param-eterized sequential systems.