[ILUG] LISP & Prologue

[Gary Mc Closkey]

----- Original Message -----
From: Kenn Humborg <kenn at linux.ie>
[snip]
> Prolog (no -ue at the end) is a different beast completely.
> It requires you to turn your brain inside out before you
> start programming it.  It's an inference language.  You tell
> it stuff (like John is big, Mary is small, Pat is small).
> Then you ask if it a statement is true (is John small?),
> or what values satisfy a statement (Who is small?).

Ha - tame stuff! One of my college lecturers helped develop a language
called FRIL (Fuzzy Relational Inference Language - I think). It was prolog
with fuzzy logic and a couple of extras thrown in. Like prolog, you give it
facts, but you can assign probability to the facts, or degrees of
uncertainty, if you like. It also allowed you to handle concepts like
'unknown', which prolog can't. You could then ask 'questions', and it would
be able to work out the answer, together with the probability of the answer.

In terms of the probability of the facts, you could tell it things like,
"I'm sure the fact is at least 10% true, and the most I'm sure the fact is
true is 80%" - very useful when you have to introduce uncertainty incurred
from measuring stuff.

. I know it all sounds a bit like something out of a Douglas Adams novel,
but apparently it was all kosher. It allowed you to do nifty things like
control logic for inherently unstable systems (e.g. fly-by-wire aircraft,
tower balancing on a movable platform) in a very small amount of code, where
a more conventional language (C) might take hundreds/thousands of decision
making statements.

I think I still have an MSDOS version of the interpreter somewhere - I'll
have to dig it out.

Gary