Acceptance trees

Abstract

A simple model, AT, for nondeterministic machines is presented which is based on certain types of trees. A set of operations, Σ, is defined over AT and it is shown to be completely characterized by a set of inequations over Σ. AT is used to define the denotational semantics of a language for defining nondeterministic machines. The significance of the model is demonstrated by showing that this semantics reflects an intuitive operational semantics of machines based on the idea that machines should only be differentiated if there is some experiment that differentiates between them.