[Ontology-editors] [OBO-Edit Working Group] Disjoint_from and symmetry

[David Sutherland]

Hiya,

On Wed, 2008-12-10 at 13:05 +0000, Jennifer Deegan (nee Clark) wrote:
> Hi,
> 
> The OBO-Edit working group would like to propose a small change to the 
> way that disjoint relationships are handled.
> 
> Currently when two terms are disjoint_from one another they each have a 
> disjoint_from relationship to the other as follows.
> 
> term1
> disjoint_from: term 2
> 
> term2
> disjoint_from: term 1
> 
As far as I can tell, the OE reasoner (LPR) copes fine with
disjoint_from only being stated in one direction, as does conversion to
OWL.  In my use I've only ever stated them in one direction.  So, there
is already no need to record disjoint_from relations in both
directions.  

However, only being able to see the relationship from one, arbitrarily
chosen side makes managing disjoints a real pain.  What is needed is for
OE to be savvy enough to display disjoint_from relations in both
directions, even when they've only been created in one direction.
However, we need to be careful about displaying disjoint_from in any
tools that display trees, as this can lead to the tools attempting to
display infinitely long branches. A text editor tab containing a list of
disjoint terms might be the easiest way to manage these things.

Cheers,

David

> However, since the disjoint_from relationship is symmetrical, it should 
> not really be necessary to have two relationships connecting two 
> disjoint terms, and the two terms should be able to share one disjoint 
> relationship. This is apparently how the situation is handled in OWL and 
> protege.
> 
> We would like to propose to start having just one relationship shared 
> between each pair of terms, as it is thought that this will greatly 
> simplify the handling of the relationships in OBO-Edit.
> We would like to hear what people think about this.
> 
> In our discussion last night we did not discuss how the OBO stanza will 
> look if there is only one relationship. We would need to discuss that 
> further, and I would be keen to hear ideas in response to this mail.
> 
> Thanks for taking the time to think about this. If we do not hear 
> objections by Friday of this week, then we will proceed to the next 
> stage of planning.

> Thanks,
> 
> Jennifer
> 
>    
> 
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