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My question goes beyond one question which already has been asked here

I defined a qualified cardinality restriction like this one:

Pizza and hasTopping exactly 4 CheeseTopping and hasTopping only CheeseTopping

Now, how do I force inconsistency of the ontology when having an individual of asserted type 'FourCheesePizza' with less than four 'CheeseTopping' property assertions?

In other words: How do I state that the let us say two 'CheeseTopping' property assertions are definitely the only ones so that an inconsistency is forced?

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MichaelKiel
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1 Answers1

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Making a statement like that is not too difficult in OWL, but because of the open world assumption, it does mean that you have to make sure that a bit more knowledge is available. First, the two-cheese-pizza, let's call it p, that will be inconsistently labelled a four-cheese-pizza must somehow be declared to have exactly two cheese toppings. You can do this by giving p the type

hasTopping exactly 2 CheeseTopping .

This would be enough to get the inconsistency. If that seems a bit generic, and you want to specify the exact toppings that p can have, you could give p a type like

hasTopping only { Cheddar, Mozzarella }

which says that p can only have Cheddar and Mozzarella as toppings. At this point, we know that p can have at most two toppings (it could be just one, if Cheddar and Mozzarella haven't been declared to be different individuals), which is inconsistent with it being a FourCheesePizza and having four cheese toppings.

Joshua Taylor
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