This volume is the latest in the Machine Intelligence Series, and it maintains the theme of the representation of machine knowledge in a wide range of disciplines. A balance is struck between theoretical and applied papers. For example, the development of Prolog to incorporate some of the features of LISP is balanced by a paper on the application of Prolog to spreadsheets. Papers on the general development of expert systems are complemented by the application of a particular expert system to forecasting weather.