Is it an insane idea to have a type of heuristic for finding a solution
that says something like:
Find at least 1 solution
Spend an hour or some amount of time looking for a better solution. If
in an hour no superior solution has been found take the first solution.
The reason I like this idea is as the speed of computers go up the
heuristic will improve automatically.
Luis Quesada wrote:
Dear Torsten,
I really like this approximation you propose. Of course, the
'progress bar' may quick go to, say, 90% and then stay there forever
and eventually fall back again. Still, that's at least some feedback..
Indeed the progress reported does not evolve monotonically. It is also
true that you may get stuck at 90%. However, this might suggest that
it is time to abort your search and have a look at the remaining 10%.
Maybe the reason why it is so hard to determine them is a bug in the
input data...
In fact, I have found this approximation useful when dealing with
tough CSP where finding one solution may take hours.
Cheers,
Luis
On 08.06.2006, at 22:47, Luis Quesada wrote:
Well, you could consider the following approximation: to associate
the status of your search with the number of variables determined
so far.
For this you got two options.
1. (naive) have a thread per variable that sends a message to a
port when the variable has been determined:
thread {Wait X} {Send P incCountOfVarsDetermined)} end
The thread reading the messages will print the status when
receiving the incCountOfVarsDetermined messages.
2. To keep a cell and update the contents of that cell at each
distribution step with the number of variables that have been
filtered out. For this you will need to write your own distributor.
Have a look at
http://www.mozart-oz.org/documentation/fdt/node40.html#chapter.user-
defined
Luis
Torsten Anders wrote:
The short answer is: this is not possible unfortunately.
To realise this you would need to know the shape of your search
tree and where the solutions are in this search tree. But if you
already know that, then there is no search required anyway -- you
would just directly go to that solution.
I'm no guru, though ;-)
Best,
Torsten
On 08.06.2006, at 21:45, Tim Heath wrote:
Hi Oz Gurus,
I want to make a kind of status bar showing how the search is
going for csp application. Any ideas how to do that? I know if
I look at the explorer it shows the tree as it is being
populated. What I am not clear on is if there is a way to know
if it is like 50% done or 75% done at any period of time
programatically.
Oz rocks!
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Torsten Anders
Sonic Arts Research Centre • Queen's University Belfast
Frankstr. 49 • D-50996 Köln
Tel: +49-221-3980750
www.torsten-anders.de
strasheela.sourceforge.net
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Torsten Anders
Sonic Arts Research Centre • Queen's University Belfast
Frankstr. 49 • D-50996 Köln
Tel: +49-221-3980750
www.torsten-anders.de
strasheela.sourceforge.net
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