```The pilog trace can be helpful in these situations.

: (be bigger (me her))
: (be bigger (her son))
: (be bigger (son daughter))
: (be bigger (@x @y) (bigger @x @z) (bigger @z @y))```
```
List the assertions you want to trace before the clause to be proved, in this
case "bigger" :

: (? bigger (bigger @x meily))

4 (bigger @x meily)
1 (bigger me her)
4 (bigger her meily)
2 (bigger her son)
4 (bigger son meily)
3 (bigger son daughter)
4 (bigger daughter meily)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
4 (bigger daughter @y)
...

So, it is infinitely recurring when trying to prove (bigger daughter @y).

The numbers in front of the pilog trace output lines correspond to the rule
being proved at that stage.

Hope that helps!

Cheers,

Doug

--- On Sun, 7/8/12, Christophe Gragnic <christophegrag...@gmail.com> wrote:

> From: Christophe Gragnic <christophegrag...@gmail.com>
> To: picolisp@software-lab.de
> Date: Sunday, July 8, 2012, 11:36 AM
> Hi all, I'm currently investigating
> Picolisp to teach prefix notation,
> and Pilog to teach first order logic.
>
> I have a problem with a set of instructions in ersatz:
>
> : (be bigger (me her))
> -> bigger
> : (be bigger (her son))
> -> bigger
> : (be bigger (son daughter))
> -> bigger
> : (be bigger (@x @y) (bigger @x @z) (bigger @z @y))
> -> bigger
> : bigger
> -> NIL
> : (? (bigger @x meily))
>  @x=alix
>  @x=sw
>
> Then ersatz freezes, no prompt.
> Any idea?
>
>
> chri
>
> --
> Envoyé de ma messagerie électronique.
> Merci de divulguer cette adresse mail au minimum (pour les
> envois en
> groupe, utilisez la copie invisible).
> --
> UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
>
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```