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From: jimc@ukc.UUCP (J.A.Crammond)
Newsgroups: net.lang.prolog
Subject: compiler bug with not?
Message-ID: <3906@ukc.UUCP>
Date: Thu, 25-Aug-83 08:48:46 EDT
Article-I.D.: ukc.3906
Posted: Thu Aug 25 08:48:46 1983
Date-Received: Mon, 29-Aug-83 16:43:55 EDT
Organization: Computing Lab. Kent University, England
Lines: 22


We have Prolog-10 version 3 running on our DEC-10 and I was testing
out the \+ evaluable predicate seeing whether the clause "\+(member(X,L)"
was any faster than an explicit "not_member(X,L)" in a program I had written.

Below are the approximate runtimes of the incore compiler and interpreter
running this program. (NB I was the only user on the system at the time).

                interpreter             compile

not_member(X,L)    2+23                   8+4

\+(member(X,L))    2+22                   8+158


The time X+Y indicates "compile time"+"execute time" in seconds.


Clearly the compiler is doing some thing VERY odd with \+(P).
Any one come across this before?

                Jim Crammond,   Leeds University.