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Learning Stochastic Logic Programs
, 2000
"... Stochastic Logic Programs (SLPs) have been shown to be a generalisation of Hidden Markov Models (HMMs), stochastic contextfree grammars, and directed Bayes' nets. A stochastic logic program consists of a set of labelled clauses p:C where p is in the interval [0,1] and C is a firstorder r ..."
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Stochastic Logic Programs (SLPs) have been shown to be a generalisation of Hidden Markov Models (HMMs), stochastic contextfree grammars, and directed Bayes' nets. A stochastic logic program consists of a set of labelled clauses p:C where p is in the interval [0,1] and C is a firstorder rangerestricted definite clause. This paper summarises the syntax, distributional semantics and proof techniques for SLPs and then discusses how a standard Inductive Logic Programming (ILP) system, Progol, has been modied to support learning of SLPs. The resulting system 1) nds an SLP with uniform probability labels on each definition and nearmaximal Bayes posterior probability and then 2) alters the probability labels to further increase the posterior probability. Stage 1) is implemented within CProgol4.5, which differs from previous versions of Progol by allowing userdefined evaluation functions written in Prolog. It is shown that maximising the Bayesian posterior function involves nding SLPs with short derivations of the examples. Search pruning with the Bayesian evaluation function is carried out in the same way as in previous versions of CProgol. The system is demonstrated with worked examples involving the learning of probability distributions over sequences as well as the learning of simple forms of uncertain knowledge.
Using Prolog to Provide Access to Metadata in an ObjectOriented Database
, 1992
"... P/FDM is an objectoriented database implemented in Prolog that is intended to provide a platform for the development of data intensive applications (e.g. scientific databases) . It is being used to store information about protein structures. A Prolog application has been developed that uses this la ..."
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Cited by 8 (3 self)
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P/FDM is an objectoriented database implemented in Prolog that is intended to provide a platform for the development of data intensive applications (e.g. scientific databases) . It is being used to store information about protein structures. A Prolog application has been developed that uses this large database to assist biochemists in homology modelling of proteins. Because of the large amounts of data involved, it is essential that database access be efficient. This is particularly true of metadata, which must be accessed several times to retrieve even a single value from the database. Unfortunately, this causes a conflict with user applications, which also need to access metadata. Now uniformity of access replaces efficiency as the main consideration. This paper examines this conflict of requirements and a solution is proposed. Finally, the suitability of Prolog for the implementation of such a solution is discussed. 1. Introduction Objectoriented databases have been proposed as s...