- From: Steven Gollery <sgollery@cadrc.calpoly.edu>
- Date: Mon, 10 Mar 2003 14:03:25 -0800
- To: www-rdf-logic <www-rdf-logic@w3.org>
Enrico, My inclination in this situation would be to make "RiversInSicily" a subClassOf "Rivers" with the restriction that the "inRegion" property is set to "Sicily". Are there circumstances where you would choose one approach over the other? Steven Gollery sgollery@cadrc.calpoly.edu Enrico Franconi wrote: >On 3/10/03 6:15 PM, Roger L. Costello wrote: > >> Can you think of a more compelling example? /Roger >> > >Consider the class "Rivers" as having properties like "inRegion", >"averageLenght", and "totalNumber". Each instance of this class is the group >of rivers in a specific region; each instance would have specified the >average length of the rivers in the group and their total number. >So, for example, an instance of "Rivers" can be "RiversInSicily", having the >property "inRegion" set to the value "Sicily", and specific numbers as >values of the properties "averageLenght" and "totalNumber". >"RiversInSicily" (which is an instance of the class "Rivers") can itself be >seen as the class of all the rivers in Sicily; properties of this class can >be the name of the river and its length. An instance of the class >"RiversInSicily" could be the "SalsoRiver", with value "Salso" for the >property "name" and value 150km for the property "length". >Obviously you may want to write a constraint saying that the count of the >rivers which are instances of "RiversInSicily" (seen as class) is equal to >the value of the property "totalNumber" of "RiversInSicily" (seen as >instance), and that the average of the lenghts of the rivers which are >instances of "RiversInSicily" (seen as class) is equal to the value of the >property "averageLenght" of "RiversInSicily" (seen as instance). > >This stuff goes back at least to the good old days of Telos (for its >theoretical foundations): >John Mylopoulos, Alexander Borgida, Matthias Jarke, Manolis Koubarakis: >Telos: Representing Knowledge About Information Systems. TOIS 8 (4): 325-362 >(1990) > >and to KEE (for its practical successful implementation): >http://www.hyperdictionary.com/dictionary/Kee >The Role of Frame-Based Representation in Reasoning, R.Fikes et al, CACM >28(9):904- 920 (Sept 1985). > >cheers >-- e. > >Enrico Franconi - franconi@inf.unibz.it >Free University of Bozen-Bolzano - http://www.inf.unibz.it/~franconi/ >Faculty of Computer Science - Phone: (+39) 0471-315-642 >I-39100 Bozen-Bolzano BZ, Italy - Fax: (+39) 0471-315-649 > > >
Received on Monday, 10 March 2003 18:40:21 UTC