In this talk, I will consider some possible extensions to existing functional programming languages that would make them more suitable for the important and growing class of artificial intelligence applications. First, I will motivate the need for these language extensions. Then I will give some technical detail about these extensions that provide the logic programming idioms, probabilistic computation, and modal computation. Some examples will be given to illustrate these ideas which have been implemented in the Bach programming language that is an extension of Haskell.

‘In successful pruning it is very necessary to know a certain amount about your subject’s mode of living. In particular it is essential to understand the factors which influence vigour, because pruning is so very much related to and governed by degree of growth. It is for these reasons that the opening pages deal with theoretical information which is of importance if the subject is to be properly understood.’ Simple Pruning, N. Catchpole, W. & H. L. Collingridge Ltd, 1930.

This paper studies a partial-match retrieval scheme based on hash functions and descriptors. The emphasis is placed on showing how the use of a descriptor file can improve the performance of the scheme. Records in the file are given addresses according to hash functions for each field in the record. Furthermore, each page of the file has associated with it a descriptor, which is a fixed-length bit string, determined by the records actually present in the page. Before a page is accessed to see if it contains records in the answer to a query, the descriptor for the page is checked. This check may show that no relevant records are on the page and, hence, that the page does not have to be accessed. The method is shown to have a very substantial performance advantage over pure hashing schemes, when some fields in the records have large key spaces. A mathematical model of the scheme, plus an algorithm for optimizing performance, is given.

In this paper, we study two new dynamic hashing schemes for primary key retrieval. The schemes are related to those of Scholl, Litwin and Larson. The first scheme is simple and elegant and has certain performance advantages over earlier schemes. We give a detailed mathematical analysis of this scheme and also present simulation results. The second scheme is essentially that of Larson. However, we have made a number of changes which simplify his scheme.