[gecode-users] CSPs with bulky static data

Christian Schulte schulte at imit.kth.se
Fri Jul 28 13:45:12 CEST 2006


Dear Torsten,

yes indeed you only need to copy data structures that contain variables
(which are typically just arrays of variables). Anything else is under your
control.

A more general basline is: whatever you want to be specific to a space you
have to copy yourself. The rest you just share among all spaces.

Cheers
Christian

-----Original Message-----
From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
Of Torsten Anders
Sent: Friday, July 28, 2006 1:11 PM
To: users at gecode.org
Subject: [gecode-users] CSPs with bulky static data 


Dear all,

I am an Oz programmer with no experience in Gecode yet, please forgive 
my newbie question.

Many of my Oz CSPs eat *very* much memory because I am using large data 
structures. Still, most data does not change at all during the search 
process, but is still copied because it is part of the script. I do 
understand that the Oz constraint store _implicitly_ incorporates 
whatever value is part of the script (computational spaces in Oz 
encapsulate speculative computations on any Oz data and each variable 
can cause a fail).

I saw that in Gecode, on the other hand, variables are _explicitly_ 
handed to the computational space. Does this mean that the Gecode user 
has explicit control what variable is incorporated in the constraint 
store (and is copied during the search process)? In other words, can a 
Gecode CSP involve large (mainly static) data structures without 
copying all the static data?

Thank you very much!

Best,
Torsten

PS: I figure I could at least reduce my problem also within Oz by 
putting my data structure outside the script and communicating between 
my script and this data only via a port. Yet, that complicates the 
definition of the CSP. Moreover, I need potentially all information 
contained in the data structure, e.g., to decide to which variables I 
what to apply constraints. I do not know whether this communication via 
a port also affects what is stored in the constraint store.

--
Torsten Anders
Sonic Arts Research Centre • Queen's University Belfast Frankstr. 49 •
D-50996 Köln
Tel: +49-221-3980750
http://www.torsten-anders.de
http://strasheela.sourceforge.net

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