[Om3] binary vs n-ary relations

[Michael Kohlhase]

David Carlisle wrote:
>>   <apply>
>>    <csymbol cd="logic1">and</csymbol>
>>    <apply><csymbol cd="relation1">eq</csmbol>a b(xml:id="foo")</csmbol></apply>
>>    <apply><csymbol cd="relation1">eq</csmbol><share href="foo"/> c</csmbol></apply>
>>   </apply>
>>
>> I must say that I like this a lot.
>>     
>
> Normally Michael liking something is reason enough to object, but he may
> have a point here.
>   
I will have to strategically rethink what I admit to liking :> to throw
you off this track, ... OTOH, I might use this reaction in the future....

So I will publicly say that I like your argument below (a lot). Another
thing that is much in favor of the OMR/share solution is that if b is
big this saves space.

Michael
> The default presentation (at least the presentation currently used in the
> CDs) goes via cmml -> OM -> pmml and currently if
>
> <apply><eq/> a b c </apply>
>
> maps to a thing with binary and and = then it will have a default
> presentation of
>
> (a = b) and (b = c)
>
> which isn't really what you want.
>
> I could make the OM->pmml stylesheet try to spot that adjacent terms are
> identical and if so use the compressed layout
> a = b = c
> but that would mean in general comparing arbitrary XMl fragments for
> equality which is a bit painful, and sometimes you may _want_ the
> expanded layout.
>
> On the other hand spotting that OMR usage is easy/quick and so it would
> be easy to generate that from <apply><eq/> a b c </apply> and conversely
> easy to give it a default presentation mathml layout of
> a = b = c
>
> David
>
>
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 Prof. Dr. Michael Kohlhase,       Office: Research 1, Room 62 
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