[jboss-jira] [JBoss JIRA] Closed: (JBRULES-1559) Ability to negate a constraint group

[Mark Proctor (JIRA)]

     [ https://issues.jboss.org/browse/JBRULES-1559?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mark Proctor closed JBRULES-1559.
---------------------------------

    Resolution: Rejected


Not sure what to do with this, so closing. Please come back with more complete suggestions if you wish to push this further.

> Ability to negate a constraint group
> ------------------------------------
>
>                 Key: JBRULES-1559
>                 URL: https://issues.jboss.org/browse/JBRULES-1559
>             Project: Drools
>          Issue Type: Feature Request
>      Security Level: Public(Everyone can see) 
>          Components: drools-compiler
>    Affects Versions: FUTURE
>            Reporter: Dirk Bergstrom
>            Assignee: Edson Tirelli
>            Priority: Minor
>
> I want to write a rule that says "Find all long-eared dogs that do not have
> short, black hair".  This seems like the simple way to do it:
> collect( Dog( ears=="long",
>                         not (hair=="short" && color=="black") )
> But that doesn't parse.  Some digging through the archives unearthed a mention
> of De Morgan's laws, which leads to: http://en.wikipedia.org/wiki/De_Morgan's_laws
> Which explains that I can instead write:
> collect( Dog( ears=="long", (hair!="short" || color!="black") )
> Which, after some mental effort, turns out to be the right thing.
> However, had I not found the reference to De Morgan's Law, it would have taken
> me a long time to get there (if indeed I ever would have).  The end result is
> also quite difficult to parse if you're not a logician, and thus not very
> user-friendly.

--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira