Re: [eclipse-clp-users] A complex Problem

From: Kish Shen <kisshen_at_...5...>
Date: Tue, 09 Feb 2010 15:11:45 +0000
Christian Wirth wrote:

> 
> if i only call getunboundmove(Player,Move,Term,State), the solution is:
> 
> Player = Player
> Move = move(north)
> Term = [d_role(Player, _219), 'd_++'(_265, _340, _219), d_cell(_264, 
> _340, _219)] - Read as: role Player exists  | _340 is _264 + 1 | cell 
> x=_263,y=_340 exists (the last var is State=_219, but these facts are 
> state independent)
> State = [location(_73, _264, _265), \+ blockednorth(_264, _265)] - 
> Player _73 is in position _264/_265 (Here _73 should be Player, but 
> thats not importent) | the north of position _264/_265 is not blocked
> 
> and for effect, i want to get:
> 
> Effects=[location(Player,_264,_340)]
> 
> It is essential, that the variable numbers are staying correct, because 
> i need to map the effects to the relevant State/Term conditions

I haven't been able to understand your code in detail, but am I correct 
in thinking that you are compiling predicates such as d_role and d_cell 
etc. in your example, which share variables (_219 in your case), and you 
expect the compiled version of these predicates will still share the 
variables?

If so, this is a rather fundamental misunderstanding of variables in 
Prolog. Variables exists during the runtime only, and variables in your 
source are not the same as the runtime variables.

If you really want to do meta-programming using compiled/asserted 
predicates with some notion about shared variables across the 
predicates, you will probably need to have some ground representation of 
variables (such as an id number) in your predicates, which you convert 
to runtime variables.

Cheers,

Kish

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Received on Tue Feb 09 2010 - 15:11:56 CET

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