- From: Enrico Franconi <franconi@inf.unibz.it>
- Date: Mon, 10 Mar 2003 22:33:57 +0100
- To: "Roger L. Costello" <costello@mitre.org>, <www-rdf-logic@w3.org>
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 16:34:36 UTC