1. 1 OWL Application The following slides are from Roger L. Costello and David B. Jacobs, The MITRE Corporation

2. 2 Scenario I am interested in purchasing a camera with a 75-300mm zoom lens size, that has an aperture of 4.5-5.6, and a shutter speed that ranges from 1/500 sec. to 1.0 sec. I launch my personal "Web Bot" which crawls the Web looking for Web sites that can fulfill my request. Assume that there exists an OWL Camera Ontology, which the Web Bot can "consult" upon its travels across the Web.

3. 3 Is this document relevant? <PhotographyStore rdf:ID="Hunts" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> Malden, MA 617-555-1234 <SLR rdf:ID="Olympus-OM-10" xmlns="http://www.camera.org#"> 75-300mm zoom 4.5-5.6 0.002 1.0 seconds 325 USD The Web Bot finds this document at a Web site: Is it relevant? (Note: SLR = Single Lens Reflex)

4. 4 A match? Match? To determine if there is a match, these questions must be answered: 1. What's the relationship between "SLR" and "Camera"? 2. What's the relationship between "focal-length" and "size"? 3. What's the relationship between "f-stop" and "aperture"? <PhotographyStore rdf:ID="Hunts" xmlns:rdf="&rdf;#"> Malden, MA 617-555-1234 <SLR rdf:ID="Olympus-OM-10" xmlns="http://www.camera.org#"> 75-300mm zoom 4.5-5.6 0.002 1.0 seconds 325 USD I am interested in purchasing a camera with a 75-300mm zoom lens size, that has an aperture of 4.5-5.6, and a shutter speed that ranges from 1/500 sec. to 1.0 sec.

5. 5 Relationship between SLR and Camera? The Web Bot "consults" the OWL Camera Ontology. This OWL statement tells the Web Bot that a SLR is a type of Camera: <PhotographyStore rdf:ID="Hunts" … Hunts.xml Web Bot Camera.owl "Relationship between Camera and SLR?" "SLR is a type of Camera."

6. 6 Relationship between focal-length and lens size? This OWL statement tells the Web Bot that focal-length is equivalent to lens size: "focal-length is synonymous with (lens) size. focal-length is to be used within a Lens. focal-length has a value that is a string."

7. 7 Relationship between f-stop and aperture? This OWL statement tells the Web Bot that f-stop is equivalent to aperture: The Web Bot now recognizes that the XML document it found at the Web site - is talking about Cameras, and it - does show the lens size, and it - does show the aperture for the camera, and - the values for lens size, aperture, and shutter speed are met. Thus, the Web Bot recognizes that the XML document is a match!

8. 8 Semantic Definitions Separate from Application! <SLR rdf:ID="Olympus-OM-10" xmlns="http://www.camera.org#"> 75-300mm zoom 4.5-5.6 <shutter-speed rdf:parseType="Resource"> 0.002 1.0 seconds 325 USD Hunts.xml Web Bot <owl:equivalentProperty rdf:resource="#aperture"/> "Relationship between Camera and SLR?" "SLR is a type of Camera." "Relationship between aperture and f-stop?" "f-stop is synonymous with aperture." "Relationship between size and focal-length?" "focal-length is synonymous with size." Camera.owl See the article "Why use OWL?" for a discussion of why it is good practice to separate the semantic definitions from the application. Semantic Definitions

9. 9 Robber and speeder example

10. 10 Robber drops gun while fleeing! First of all a robbery takes place. The robber drops his gun while fleeing. This report is filed by the investigating officers:... ABCD

11. 11 Speeder stopped Subsequently a car is pulled over for speeding. The traffic officer files this report electronically while issuing a ticket:... Fred Blogs ZXYZXY

12. 12 The speeder owns a gun with the same serial number as the robbery gun! At police headquarters (HQ), a computer analyzes each report as it is filed. The computer uses the driver's license information to look up any other records it has about Fred Blogs (the speeder) and discovers this gun license: ABCD ZXYZXY

13. 13 Case solved? ABCD ZXYZXY How many guns can have this serial number? How many people can have this driver's license number? Can this gun be registered in other gun licenses? How many guns/people are registered in a gun license? 1 2 3 4

14. 14 Can multiple guns have the same serial number? This OWL statement tells the computer at police HQ that each gun is uniquely identified by its serial number: ABCD Only one gun can have this serial number. 1

15. 15 Can multiple people have the same driver's license number? The following OWL statement tells the computer that a driver's license number is unique to a Person: Only one person can have this driver's license number. 2 ZXYZXY

16. 16 Can a gun be registered in multiple gun licenses? The next OWL statement tells the computer that the registeredGun property uniquely identifies a GunLicense, i.e., each gun is associated with only a single GunLicense: ABCD... A gun can be registered in only one gun license. 3

17. 17 Can a gun license have multiple holders of a registered gun? The police computer uses the following OWL statement to determine that the gun on the license is the same gun used in the robbery. This final statement seals the speeder's fate. It tells the computer that each GunLicense applies to only one gun and one person. So, there is no doubt that the speeder is the person who owns the gun: 1 1...... A gun license registers one gun to one person. 4