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Issues with ubuntu 18.04


From: Jerry Hancock
Subject: Issues with ubuntu 18.04
Date: Thu, 25 Mar 2021 14:25:54 -0700

Hello,  

Please excuse me for asking about something so old.  I installed gnu-prolog 1.4.5 on ubuntu server 18.04.  The underlying hardware is an HP dl380 with at least 24 cores.  I had some code that runs perfectly but slowly on other servers so I thought I would try my cloud server.

The test code is simple and instantiated in sit3.pl:

c(blue).
c(green).

sit3(X):-c(X).

On my other installations, the first solution X=blue is returned as expected..  On the ubuntu server 18.04 , I get an error, "uncaught exception error(existence_error(procedure,c/0),sit3/0) “ implying that c/0 doesn’t exist but I’m not calling c/0 I’m calling c/1 as below:

{trace}
| ?- sit3(X).
      1    1  Call: sit3(_24) ? 
      2    2  Call: c ? 
      2    2  Exception: c ? 
      1    1  Exception: sit3(_24) ? 
uncaught exception: error(existence_error(procedure,c/0),sit3/0)
{trace}
| ?- 

If I assert the clauses from the terminal, all is well.

If I run c(X), trace returns:

| ?- c(X).
      1    1  Call: c(_24) ? 
      1    1  Exit: c(blue) ? 

X = blue ? 

Or 

| ?- asserta(cc(blue)).

yes
| ?- asserta(cc(green)).

yes
| ?- asserta((sit33(X):-cc(X))).

yes
| ?- sit33(X).

X = green ? 


This is a very simple example that should work.  I’ve been working with prolog since the late 80’s and unless there is an ini file that is note allowing the clauses to be added correctly, I could't find it.

Thanks

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