[rules-users] Re: drools-solver - magic name of scoreCalculator => Solution has a Sore and is inserted into the working memory
Geoffrey De Smet
ge0ffrey.spam at gmail.com
Sun Feb 15 10:03:44 EST 2009
I am actually considering a couple of designs, which also happens to
solve the problem of the magic name of the scoreCalculator.
1) a score will no longer be a double, but an instance of a new
interface Score. This will means that a score of an int hard and int
soft will be represented as it should be: an int hard and an int soft.
That has 2 advantages:
- you could use implement their own Score, if the out-of-the-box types
don't suffice, say int hard, BigDecimal soft, double verySoft.
- it would be possible to decide the step, not on a normal compareTo,
where hard is always higher then soft, but on (hard * hardAsSoftWeight +
soft), where hardAsSoftWeight changes:
it's normally very high, but when no hard constraints are broken in a
long time, it temporarily goes down.
This allows the local search to take steps that break a hard constraints
for a while, passing through hard barriers. Experiments have proven that
this gives better results.
2) a Solution has a Score. That Score can be uninitialized or dirty.
A Solution is also inserted into the working memory (along with it's facts).
Every changing fact (Queen, Lesson, Exam, ...) will also need to hold a
reference to it's Solution.
That way every ConstraintOccurrence can hold a reference to it's Solution.
Then the calculateScore rule will update the score in a solution,
instead of putting it into a global. The solver still has a reference to
the solution, so it can retrieve the score.
This allows for multiple solution instances to be put into same working
memory and there's no magic scoreCalculator.
What do you think? Criticism welcome :)
Of course, backward compatibility will be broken (as stated in the
manual), but everything will be documented into an upgradeRecipe.txt,
so it shouldn't be to hard to upgrade to a newer version.
With kind regards,
Geoffrey De Smet
Greg Barton schreef:
> Actually, I was wishing for something similar last night, but for the names of entry-points. I think it would be nice if you could specify the names of things in DRL from the values of public static final Strings. (i.e. constants) Do you dev folk think that's possible enough to make a jira request for it?
>
> --- On Fri, 2/13/09, Geoffrey De Smet <ge0ffrey.spam at gmail.com> wrote:
>
>> From: Geoffrey De Smet <ge0ffrey.spam at gmail.com>
>> Subject: [rules-users] Re: drools-solver - magic name of scoreCalculator
>> To: rules-users at lists.jboss.org
>> Date: Friday, February 13, 2009, 9:37 AM
>> Yes, it's not that good that it's a magic name.
>> However, I don't know any other way to do it.
>> Feel free to make a jira for it, especially if you know a
>> better way to do it :)
>>
>> With kind regards,
>> Geoffrey De Smet
>>
>>
>> Andrew Waterman schreef:
>>> Thanks Geoffrey! I patched this yesterday with
>> slf4j-jcl and slf4j-nop for no loging. I'll post the
>> mavne dependencies later this morning in case others wish to
>> use non-log4j implementations. :) I did noticeas well that
>> the "scoreCalculator" global is referenced by name
>> from the solver. Want me to file a jira issue on that? It
>> seems strange that the variable name shoudl be static like
>> that to me.
>>> best wishes,
>>>
>>> Andrew
>>>
>>> On Fri, Feb 13, 2009 at 7:55 AM, Geoffrey De Smet
>> <ge0ffrey.spam at gmail.com
>> <mailto:ge0ffrey.spam at gmail.com>> wrote:
>>> Adding the slf4j-log4j12 dependency to your
>> pom.xml should fix it :)
>>> <dependency>
>>>
>> <groupId>org.slf4j</groupId>
>>>
>> <artifactId>slf4j-log4j12</artifactId>
>>> <scope>runtime</scope>
>>> </dependency>
>>>
>>> Not sure how changing anything in
>> drools-solver-examples could fix
>>> it, normally your project wouldn't depend on
>> it, only on
>>> drools-solver-core.
>>>
>>>
>>> With kind regards,
>>> Geoffrey De Smet
>>>
>>>
>>> Greg Barton schreef:
>>>
>>> I was getting the error below running the
>> benchmarkNQueens.sh
>>> script in drools-solver-examples. I got
>> around it by taking the
>>> "<scope>runtime</scope>"
>> line out of the slf4j-log4j12
>>> dependency in drools-solver-examples/pom.xml.
>> Not sure if
>>> that's the right way to get around it, but
>> it worked. :)
>>> --- On Fri, 2/13/09, Geoffrey De Smet
>> <ge0ffrey.spam at gmail.com
>>> <mailto:ge0ffrey.spam at gmail.com>>
>> wrote:
>>> From: Geoffrey De Smet
>> <ge0ffrey.spam at gmail.com
>>> <mailto:ge0ffrey.spam at gmail.com>>
>>> Subject: [rules-users] Re: drools-solver
>> -- logger error
>>> (slf4j binding)?
>>> To: rules-users at lists.jboss.org
>>> <mailto:rules-users at lists.jboss.org>
>>> Date: Friday, February 13, 2009, 1:04 AM
>>> drools-score (like hibernate and many
>> other lib projects)
>>> just depends on sl4j-api, which is a
>> logging interface.
>>> It's up to the end-use product to
>> decide which logging
>>> implementation to use under that and how
>> to configure the
>>> logging (where to log to, how much to log,
>> ...).
>>> In the drools solver examples I 've
>> put slf4j-log4j
>>> underneat it, because I am familiar with
>> log4j's
>>> configuration, take a look at their
>> log4j.xml files. However
>>> they say that the logback implementation
>> is better these
>>> days.
>>>
>>>
>>> PS: I 'll take a look at the other
>> discussions this
>>> afternoon.
>>>
>>> With kind regards,
>>> Geoffrey De Smet
>>>
>>> Andrew Waterman schreef:
>>>
>>> Hi,
>>>
>>> I'm using the drools-solver.M5
>> build through Maven
>>> and have gotten the following error while
>> running my
>>> project:
>>>
>>> SLF4J: Failed to load class
>>>
>>>
>> "org.slf4j.impl.StaticLoggerBinder".
>>> SLF4J: See
>>>
>>>
>> http://www.slf4j.org/codes.html#StaticLoggerBinder for
>>> further details.
>>>
>>> I've checked my dependency graph,
>> and
>>> drools-solver references the sl4j-api, but
>> no
>>> implementation. I checked the
>> mvnrepository, and there are
>>> several other slf4j related projects.
>> What is the preferred
>>> binding for JDK1.6?
>>>
>>> best wishes,
>>>
>>> Andrew
>>>
>>> ---------------------------------
>>> Andrew Waterman
>>> San Cristóbal de las Casas, Chiapas,
>> Mexico
>>> +52 1 967 107 5902
>>> +1 510 342 5693
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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