| 14 | | ISO 15926 classifies plant objects using an open, extensible Ontology. |
| 15 | | |
| 16 | | ---- |
| 17 | | |
| 18 | | == How We Know and Understand Things == |
| 19 | | |
| 20 | | When we go beyond custom-built methods to exchange information between two particular computer applications--when we try to design a way for any two random computer applications to connect to each other automatically without having to know anything at all about each other--we confront the question of how we represent knowledge. This is not just sophistry; if two computer systems are to connect to each other automatically, we must have a way to embed the necessary context (the understanding that humans bring) within the data that is being exchanged. For this we need to understand how we know things. The study of how we know things in philosophy and mathematics is called ''ontololgy''. |
| 21 | | |
| 22 | | ''Philosophy, sufficiently advanced, is indistinguishable from bulls**t.[[BR]] --Greg Berge'' |
| 23 | | |
| 24 | | === Ontology === |
| 25 | | |
| 26 | | The study of ontology is well beyond what most people will need to know in order to use ISO 15926, and therefore beyond the scope of this primer. However, a brief example to explain what ''ontology'' is will be helpful: |
| 27 | | |
| 28 | | Your humble author rides a bicycle to work most days. (Among other things, it lets me indulge in the luxury of eating the fine Ukrainian food my wife cooks for me!) The distance to work makes a nice workout but is beyond walking if the bicycle were to break down. Therefore, I have developed what you might call an ''Ontology'' ''of'' ''Things'' ''That'' ''Will'' ''Carry'' ''A'' ''Bicycle.'' |
| 29 | | |
| 30 | | Now, in Western Canada, which to most Europeans is but a few years out of the horse age, the pickup truck is king. In Western Canada, all ''Real'' ''Men'' have pickups. As you can see from Figure 3, there is ample room in a pickup truck to carry a bicycle. |
| 31 | | |
| 32 | | [[Image(History_PickupTruck.JPG, 150px)]] |
| 33 | | |
| 34 | | '''Fig 3 - Pickup Truck''' |
| 35 | | |
| 36 | | So it is not hard to imagine that if my bicycle broke down on the way to work, I would try to think of everyone who owned a pickup truck that might have driven it to work that day. Suppose one such friend is Bill, who owes me a big favor. But when I talk to Bill he tells me he can't help me. He tells me he is going camping that weekend and to make a fast getaway he's already loaded his camper. How do I know this will be a problem? Because I know that when you load a "camper" onto a pickup truck, there is no room for a bicycle. |
| 37 | | |
| 38 | | [[Image(History_Camper.JPG, 150px)]] |
| 39 | | |
| 40 | | '''Fig 4 - Pickup Truck with a Camper Loaded''' |
| 41 | | |
| 42 | | But hold on! My father used to own a camper for his own pickup truck (he being a ''Real'' ''Man'' and all), and I remember looking inside it. There was space just inside the door that might be able to fit a bicycle. Alas, Bill tells me, he has already filled the available space with his other camping gear, leaving no room. |
| 43 | | |
| 44 | | So with that conversation, I start planning how to get home on public transit. Being a ''Real'' ''Man'' myself, I own a pickup truck and will have to drive it back to work to pick up my bicycle. But by coincidence, a new engineer, who's just emigrated from the Czech Republic, walks by and overhears my dilemma. He tells me that when he moved to Canada, he brought with him his ''Felicia'' ''Fun''. I can't imagine what a ''Felicia'' ''Fun'' is, but judging by the expectant smile on his face I suspect it might be relevant so I ask him about it. Being new to Canada he doesn't know how to describe it so he says it is like the F150 his friend has, but a bit smaller. (The Czech Republic has ''Real'' ''Men'' too!) I immediately accept his kind offer to drive me and my bicycle home after work. (Oh, and I owe him a ''really'' big favor. Perhaps I will invite him in for Ukrainian food!) |
| 45 | | |
| 46 | | How did I know that a ''Felicia Fun'' would carry my bicycle? Because it is "like an F150", which is the name of a particular brand of pickup truck common in North America. Figure 5 shows the relationship of things in my ontology. |
| 47 | | |
| 48 | | [[Image(History_OntologyBicycle.JPG, 400px)]] |
| 49 | | |
| 50 | | '''Fig 5 - Ontology of Things That Will Carry A Bicycle''' |
| 51 | | |
| 52 | | This example is all most people will ever have to know about ontology. But if you are interested in digging deeper, the W3C Consortium has created two languages with which to create ontologies, Resource Description Framework (RDF), and the Web Ontology Language (OWL). Neither are for the feint of heart. |
| 53 | | |
| 54 | | * [http://www.w3.org/TR/rdf-primer/ RDF Primer] |
| 55 | | * [http://www.w3.org/2003/08/owlfaq.html Frequently Asked Questions about OWL] |
| 56 | | |
| 57 | | |
| 58 | | == NEXT == |
| 59 | | |
| 60 | | * [wiki:ISO15926Primer_History_UseInternet Primer: How We Use The Internet To Find Information] |
| 61 | | |
| 62 | | ---- |
| | 13 | * [wiki:ISO15926Primer An Introduction to ISO 15926] |
