"Computable functionals on non-flat data types" (Helmut Schwichtenberg)

We present a denotational semantics of a common extension T^+ of T (Goedel) and PCF (Plotkin), operating over the Scott-Ershov partial continuous functionals. The base domains are taken to be non-flat data types, because we want the constructors to be injective and with disjoint ranges. It is shown that Plotkin's definability theorem can be transferred to the present setting (joint work with Basil Karadais).