closed available at http://www.kestrel.edu/DAML/2000/12/TIME.daml 12-14-2000 17:44 becker@kestrel.edu $Id$ Kestrel Scheduling Ontology This ontology is based on the time ontology available from Stanford's ontoserver. Other groups also defined time ontologies in DAML: http://www.ai.sri.com/daml/ontologies/sri-basic/1-0/Time.daml http://www.cs.cmu.edu/~softagents/atlas/ontologies/atlas-date.daml But they do not provide all the entities needed in a scheduling domain. From KSL - Simple-Time ontology "A time-point is a point in real, historical time (on earth). It is independent of observer and context. A time-point is not a measurement of time, nor is it a specification of time. It is the point in time. The time-points at which events occur can be known with various degrees of precision and approximation, but conceptually time-points are point-like and not interval-like. That is, it doesn't make sense to talk about what happens during a time-point, or how long the time-point lasts." Although one can think of TimePoint as an integer representing an offset from a certain TimePoint considered to be the start of the time scale, we will represent a time point as a subclass of daml:#Thing and would use a property to express the value of the time point with respect to a certain reference point using a certain unit of measure or time glanularity. For now, assume the value of a time point to be expressed by an integer representing a number of certain time units since the origin of the time scale. The Time-Unit represents the granularity of the time representation. The property time of a TimePoint represents the number of time units since a certain time point TimeZero. Using small letters to represent a property that has as domain the class with the same name as the property but starting with capital letter. This has been based on http://www.cs.cmu.edu/~softagents/atlas/ontologies/atlas-date.daml. But I do not add the month names in the definition of the class since the names are just literals. Is it correct to define all the member of the class using the oneOf construct? Trick to get the correct restiction on seconds and minutes without having to define a class Seconds and Minutes Again, how do I express the value of an Integer?? Trick to get the correct restiction on hours without having to define a class Hours Again, how do I express the value of an Integer?? Trick to get the correct restiction on days and minutes without having to define a class Day. Again, how do I express the value of an Integer?? The name of the week day. A calendar class provides rules on how to translate the time property of a TimePoint object into a Date object expressed in terms of month, day, etc.. Maybe Date should be a sub-class of Calendar. Here I based the ontology on the Java API that defines an abstract class Calendar, and a separate class for representing the date. In the Java implementation, however, the class Date is equivalent to the class TimePoint. A date is the entity that provides a representation for a time point in a given calendar. It has properties day, second, minute, hour, year. I will restrict the values of the properties in the class definition. I am here using a construct presented in DAML-OIL and not standard DAML. How do I say that the value of a certain property should be in a certain range?? The default DAML syntax for restriction uses the onProperty/hasValue or onProperty/toClass construct. The problem with these types of construct is that I can only constrain the range of a property value to belong to a certain class. For example, if I want to say that the value of the property second is an integer between 0 and 59, I need to declare a class, for example Seconds, and constrain the its values to be between 0 and 59. Then I can use this class in the toClass construct. The problem is that if I wand to use seconds that go only from 0 to 30, I need to declare a new sub-class of Seconds. How can I restrict only the value without having to create a new class every time I need to impose restrictions. How can I refer to the value of a certain property? This class is characterized by a pair of TimePoints and a given duration representing the difference between the two time points The duration is just the difference between the endTimePoint and the startTimePoint of the interval Sequence of time interval defining a temporal profile The temporal relation is the super class to represent relations between Time-Points and Time-Intervals.