Problem on defined classes, multiple sets of N-A conditions, and synonym

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Problem on defined classes, multiple sets of N-A conditions, and synonym

Jinyue

Hello,

 

I am almost finishing the pizza ontology followed the P4 guide. Here are some problems I encountered.

 

1.       defined classes

 

on the page 57 of the guide, the exercise 29 asks to convert the necessary condition “hasTopping some ChesseTopping” and “Pizza” to necessary and sufficient condition. I understand the drag and drop problem, so I cut the two items and then past them under the “Equivalent class” header. Based on the guide, I should get these two item unionized together, but I got two separate items, which is obviously wrong (the class Pizza is equivalent to the class CheesyPizza). I don’t know how to past an item (for example the “Pizza”) onto another item (for example “hasTopping some ChesseTopping”). I did some research and downloaded the pizza.owl and found the condition should be “Pizza and hasTopping some ChesseTopping”. I can edit it to get correct defined class CheesyPizza, but hope to have an easier way to make it. Is it possible?

 

I am also confused by class icons. The guide said defined classes have a class icon with an orange background, and primitive classes have a class icon with yellow background. It looks the background color for both kinds of classes are same, the only different is the defined class icon has an “identical” (three short lines) symbol on the icon. On the page 57 of the guide, the figure 4.45 shows a big icon to unionize the two items under “Equivalent class” header, but I never saw such icon. I also did not see any icon with logical symbol. I only saw two kinds of icon, one is big yellow dot, another is the icon for defined classes (big yellow dot with identical symbol). Did I miss something out?

 

2.       multiple set of necessary and sufficient criteria

 

With the confusion of question 1, I can not define more than one N-A criteria, can I?

 

3.       Synonym

 

How do you deal with synonym? Using defined classes (equivalent classes)? For example, I have ClassA and ClassB as synonym, both are the subclass of ClassD. Shall I do this: create ClassA and ClassB as the subclasses of ClassD, then define ClassB as the equivalent class of ClassA? It seems reasonable, but I got something strange under “inherited anonymous class” header, for ClassA, ClassB showing there with a line cross it out, for ClassB, ClassA showing there with a crossing line. I can not remove them by clicking the big X on the right. If I made three classes equivalent each other, I had two or three this kind of crossing classes under the “inherited anonymous class” header. What is wrong there?

 

4.       Last, can I suggest to, in section 4.11 of the guide, introduce more background on setting OWLViz? I spent pretty much time on searching the Web to find how to get GraphViz DOT application installed and point the DOT to the correct folder. GraphViz is not packed with P4.

 

Thank you very much.

 

Jinyue Zhang @ University of Toronto

 

 


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Re: Problem on defined classes, multiple sets of N-A conditions, and synonym

Nick Drummond
Thanks for the feedback Jinyue.

Comments inline...

On 9 May 2008, at 03:27, Jinyue Zhang wrote:

Hello,
 
I am almost finishing the pizza ontology followed the P4 guide. Here are some problems I encountered.
 
1.       defined classes
 
on the page 57 of the guide, the exercise 29 asks to convert the necessary condition “hasTopping some ChesseTopping” and “Pizza” to necessary and sufficient condition. I understand the drag and drop problem, so I cut the two items and then past them under the “Equivalent class” header. Based on the guide, I should get these two item unionized together, but I got two separate items, which is obviously wrong (the class Pizza is equivalent to the class CheesyPizza). I don’t know how to past an item (for example the “Pizza”) onto another item (for example “hasTopping some ChesseTopping”). I did some research and downloaded the pizza.owl and found the condition should be “Pizza and hasTopping some ChesseTopping”. I can edit it to get correct defined class CheesyPizza, but hope to have an easier way to make it. Is it possible?
 

I've updated the errata [1] for page 57 to include the right click "Convert selected rows..."

I am also confused by class icons. The guide said defined classes have a class icon with an orange background, and primitive classes have a class icon with yellow background. It looks the background color for both kinds of classes are same, the only different is the defined class icon has an “identical” (three short lines) symbol on the icon. On the page 57 of the guide, the figure 4.45 shows a big icon to unionize the two items under “Equivalent class” header, but I never saw such icon. I also did not see any icon with logical symbol. I only saw two kinds of icon, one is big yellow dot, another is the icon for defined classes (big yellow dot with identical symbol). Did I miss something out?
 

No, the set of icons has changed. I have added a note in the errata.

2.       multiple set of necessary and sufficient criteria
 
With the confusion of question 1, I can not define more than one N-A criteria, can I?

Yes, you can just press the + button by the equivalent classes to add a new equiv on this class - there is no limit.
Or just repeat the steps you took to create the first.

 
3.       Synonym
 
How do you deal with synonym? Using defined classes (equivalent classes)? For example, I have ClassA and ClassB as synonym, both are the subclass of ClassD. Shall I do this: create ClassA and ClassB as the subclasses of ClassD, then define ClassB as the equivalent class of ClassA? It seems reasonable, but I got something strange under “inherited anonymous class” header, for ClassA, ClassB showing there with a line cross it out, for ClassB, ClassA showing there with a crossing line. I can not remove them by clicking the big X on the right. If I made three classes equivalent each other, I had two or three this kind of crossing classes under the “inherited anonymous class” header. What is wrong there?
 

The crossing out is a bug (fixed in the next build). Do not worry about it. If I were creating synonyms, I would avoid creating multiple classes - one for each - just provide multiple labels as annotations for the same class. If you are using someone else's ontology that defines ClassA and you have defined ClassB and they are equivalent then fair enough.


4.       Last, can I suggest to, in section 4.11 of the guide, introduce more background on setting OWLViz? I spent pretty much time on searching the Web to find how to get GraphViz DOT application installed and point the DOT to the correct folder. GraphViz is not packed with P4.
 

We cannot distribute graphviz with P4 because of licensing. There is documentation for OWLViz available here [2]

Thank you very much.
 
Jinyue Zhang @ University of Toronto
 
 

Nick


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