Preface - Version Beta

A number of people have asked me to make this system, along with its documentation, available to the public. Now that it's available, I hope that it's useful. But a word of caution is in order. The system is still only a prototype, hence the label ``version $\beta$.''

Any bug reports would be greatly appreciated. But what I'd really like is comments on the functionality of the system, as well as on the utility of its documentation. I am also interested in hearing of any applications that are made of the system. I would also be glad to answer questions about the system. I have tried to document the strategies used by ALE in this guide. I have also tried to comment the code to the point where it might be adaptable by others. I would, of course, be interested in any kind of improvements or extensions that are discovered or developed, and would like to have the chance to incorporate any such improvements in future versions of this package.

In the implementation, I have endeavored to follow the logic programming methodology laid out by O'Keefe (1990), but there are many spots where I have fallen short. Thus the code is not as fast as it could be, even in Prolog. But I view this system more as a prototype, indicating the utility of a typed logic programming and grammar development system. Borrowing techniques from the WAM directly, implementing an abstract machine C, would lead to roughly a 100-fold speedup, as there is no reason that ALE should be slower than Prolog itself.

I would like to acknowledge the help of Gerald Penn in working through many implementation details of a general constraint resolver, which was the inspiration for this implementation. This version of the system is a great improvement on the last version due to Gerald's work on the system. Secondly, I would like to thank Michael Mastroianni, who has actually used the system to develop grammars for phonology. Finally, I would like to thank Carl Pollard and Bob Kasper for looking over a grammar of HPSG coded in ALE and providing the impetus for the inclusion of empty categories and lexical rules.

The system is available without charge from the author. It is designed to run in either SICStus or Quintus Prologs.
Bob Carpenter
Pittsburgh, 1992