Thomas N. Hibbard

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much more efficient internal sort than either of the four techniques previously published. The additional space required is one word per record. Therefore, given a memory area of size A and a record of size S, then the number of records (N) that can be sequenced in memory using the Replacement Selection technique is A/(S+i), as compared to A/S for other(More)
A preliminary example of program development demonstrates that the control-independent implementation of data types can lead to very inefficient code. The concept of a data space, which emphasizes the interaction between data and control structures, is introduced as a formal model of virtual machines. The model consists of three components: a state space X,(More)
A phrase structure grammar is called <italic>context-limited</italic> if there exists a partial ordering on its alphabet such that any letter on the left of any production is less than some letter on the right of the same production. It is proved that context-limited grammars are equivalent to context-free grammars, the equivalence including ambiguity. The(More)