A New Characterization of Lambda De nability
نویسندگان
چکیده
We give a new characterization of lambda deenability in Henkin models using logical relations deened over ordered sets with varying arity. The advantage of this over earlier approaches by Plotkin and Statman is its simplicity and universality. Yet, decidability of lambda deenability for hereditarily nite Henkin models remains an open problem. But if the variable set allowed in terms is also restricted to be nite then our techniques lead to a decision procedure.
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