[Attempto] counting, maximum, sums

[Norbert E. Fuchs]

On 3 Dec 2010, at 20:42, Jean-Marc Vanel wrote:

> ACE has a notion of counting sets, like :
> XYZ is a product and it has exactly 3 parts.
> 
> But as far as I know, it's not possible to say something about a cardinality not assigned to a value, like:
> If X is a product and it has a number of parts N then N is equal to the number of workers for X .
> 
> The issue is similar for sentences involving maxima, minima, and sums.
> 
> So the questions are: what are in ACE the possibilities to express notions  like counting, maximum, minimum, summation.
> If nothing special , how difficult would it be to implement that ?
> 
> Note that some Knowledge Representation langages like DLV have a formalism for that :
> http://www.dlvsystem.com/dlvsystem/html/DLV_User_Manual.html#AEN814
> N3 also has extensions .

Jean-Marc

The syntax of ACE allows you to express counting, maximum, minimum, sum etc., but the ACE parser does not implement the respective functionality. Thus the ACE parser accepts the sentence 

   {1,2,3} is a set that has 15 elements.

as syntactically correct without checking its semantics. The semantics – i.e. the functionality of counting, maximum, minimum, sum etc. – must be provided by the tools that use ACE.

Your statement 

> ACE has a notion of counting sets, like :
> XYZ is a product and it has exactly 3 parts.

could be misleading since the ACE parser does not check – and has no means to check – that XYZ has 3 parts. 

Regards.

   --- nef