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Topic: PROLOG ENGINES ARE REALLLLLLY SLOW! ((SQL-UNIFY))
Replies: 5   Last Post: Nov 20, 2012 4:40 PM

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Jan Burse

Posts: 463
Registered: 4/12/05
Re: PROLOG ENGINES ARE REALLLLLLY SLOW! ((SQL-UNIFY))
Posted: Nov 20, 2012 10:46 AM
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Graham Cooper schrieb:
> A lot of variable renaming conventions, trial and error,
> backtracking... very tricky and particular code covering
> dozens of potential matching scenerios!


Already efficiently solved to some extend in the 70's. Have
a read about the early childhood of Prolog systems:

La naissance de Prolog
Juillet 1992, A. Colmerauer, P. Roussel
http://prolog.developpez.com/tutoriels/alain-colmerauer/histoire-prolog/fichiers/histoire-prolog.pdf

> Slight drawback is program order is lost using the fastest match
> method, but PROLOG is overused as a simple FETCH cycle for 3GL style
> coding.


Add an additional sorting column, and you can preserve the input order.
Any Prolog system implementing multi-argument indexing has also to
solve this problem, in that the index lookup bust deliver a clause set
which is actually a clause list ordered by the input order.

Bye




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