Abstract The construction of minimal acyclic deterministic partial finite automata to represent large natural language vocabularies is described. Applications of such automata include spelling checkers and advisers, multilanguage dictionaries, thesauri, minimal perfect hashing and text compression.

Abstract The relationship between parameter passing mechanisms and run time data structures in languages with statically‐nested scopes is examined. It is shown that simpler data structures can be used in some cases, with increased efficiency in accessing non‐local variables. In particular it is true for the call‐by‐value‐result mechanism, where the usage of displays can be eliminated altogether; however there is some additional cost associated with procedure calls. Under certain conditions the same implementation applies to call‐by‐reference.

A techmque for proving correctness of programs manipulating data structures Is proposed.Its three major components are' (i) an abstract representation for the data structures called free state description (FSD), (n) a set of propositions which allow transformations of such FSD's, and (in) semanacs of assignment statements m terms of FSD transformations.The techmque provides a framework for rigorous proofs about programs manipulating data structures with arbitrary sharing of pointers and circularmes Examples of apphcauons include the Deutsch-Schorr-Waite markmg algorithm A grapincal mterpretatzon of proofs is sketched to illustrate the intumve concepts hidden behmd this technique The method extends the one devised by Burstall by allowing arbitrary data structures.