Structured data structures

Much attention has been focused lately on the notions of structured programming, a crucial factor when dealing with the design of large programming Systems. Rather than viewing programming as an art and the programmer as the perpetual artist, structured programming provides a more .systematic (and in a way more restricted) approach which facilitates debugging and proving assertions about programs. One of the ideas developed by advocates of structured programming is the topdown elaboration of program control structures by a recursive process of successive refinements [i]. No such process has been developed for dealing with data structures. The main reason for this is the improper intermixing of the semantic and implementation concepts [2] of a data structure. The failure to distinguish between these concepts is a result of the conflicting factors involved in choosing a data structure: Simplicity of element access, minimization of search time, dynamics of growth or elimination of data, simplicity of restructurlng and extension, efficiency of storage utilization and others.