Thus he presents the first systematic effort to provide a computational model with a logical basis. Computational models have broad application of programming language semantics and specification language, through language and knowledge representation formalism for natural language semantics. They also implied in computer modeling of many physical and social sciences. This detailed investigation into the logical basis of language specification and the specification and its application to the definition of programming languages, coupled with a clear exposition of the theory of data and computational models as mathematical ideas will be welcomed by researchers and graduate students.