Re: some basic questions, thanks

Li Qin wrote:
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2. "If A is the subclass of union of B and C" does not mean that A is the union of B and C. My question concerns the case that A is the union of B and C. If A is the union of B and C, the instances of B and C are instances of A.  If A is the superclass of B and C, the instances of B and C are instances of A. What is the difference?
3. ...Does this unkown class the union of A and B or the superclass of A and B?
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Yuzhong Qu's  reply
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* The properties of a superclass are applicable to the instances of the subclasses.

* Just guess, use the union structure
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Pat Hayes 's comment:
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That is not quite correct. The properties which apply to the elements of a superclass are applicable to the instances of the subclasses: but that is because those instances are the very same things as the instances of the superclass.

It is the union, which is a superclass of both.
]

Does it mean that "If A is the union of B and C, then A is a superclass of both B and C"?

Where does the entailment come from?


Yuzhong Qu
Dept.Computer Science and Engineering
Southest University, Nanjing, China
http://cse.seu.edu.cn/People/yzqu/en

Received on Sunday, 21 September 2003 22:28:04 UTC