From: Jeff Heflin ([email protected])
Date: 10/31/01
Hi everyone, Some of my students have tried running the daml+oil-ex.daml example [1] through BBN's DAML Validator [2] and suprisingly received 27 indications of potential problems. Fortunately, many of these errors are due to limitations of the validation tool, but a few are errors in the example. Below, I discuss the errors found by the Validator, and for each suggest whether the bug is in the Validator or the example. 1) The Santa example creates an associatedData of type xsd:real, but XML Schema does not define a real datatype. This should probably be changed to xsd:decimal, xsd:float, or xsd:double in the example. 2) The Person class has a restriction stating the a person can have only one FullTimeOccupation, but FullTimeOccupation is not defined in the ontology. The FullTimeOccupation class should be added to the ontology. 3) BigFoot is an rdfs:Class instead of a daml:Class. However it is used in the domain of intersectionOf, which requires a daml:Class, generating a domain type mismatch error. The example should be changed. 4) The Validator raises an error because hasMom is samePropertyAs hasMother, but hasMom is an ObjectProperty and hasMother is a UniqueProperty (which could be an ObjectProperty or DatatypeProperty). Personally, I don't think this should be an error; it should only be an error if you say an ObjectProperty is samePropertyAs a DatatypeProperty. I'd like to get the committee's opinion on the situation. 5) The Validator raises errors anytime a cardinality restriction is violated. In the case of the example, this is mostly because Adam, Santa, Peter, and Ian do not have any parents mentioned. I don't think an error should be raise here, because other values for the property may be found on other web pages. One possibility, is to raise an error only when a maximum cardinality constraint is violated, but even in this case, it is possible that an as yet undiscovered equivalentTo property will be found, reducing the total number of distinct values. Therefore, I suggest that all violations of cardinality constraints be presented as warnings (not errors), but would like feedback from the rest of the committee. 6) The Validator generates a number of errors because it doesn't support the daml:collection parse type yet. Hopefully, that will be fixed in the near future. What this situation indicates to me, is that we need a much clearer description of exactly how should treat a DAML document, i.e., what results in an error, what results in a warning, etc. Do you think this is an issue for the Joint Committee or the WebOnt working group? Jeff [1] http://www.daml.org/2001/03/daml+oil.daml [2] http://www.daml.org/validator/
This archive was generated by hypermail 2.1.4 : 04/02/02 EST