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Create an instance of person that will represent John
in the hierarchy.
From the previous step, the Object Hierarchy should look like
the following:
 1
1001
1002
Now we will create an instance of person that will represent John.
To do this, press the instantiate icon
for the class
of id 1001. This should create a new instance under the 1001 class
and make the view look like the following:
1
1001
 1003
1002
The new instance, id 1003, is shown as a child of the class we instantiated,
id 1001. Note that the instantiate and subclass icons are missing from the
instance object, because instances cannot be instantiated or subclassed.
A new icon was added to the object id 1001. The open icon
allows the user to close entire
subtrees of the hierarchy for easier browsing by displaying less objects
on the screen. If a class has child classes or instances that are not shown,
the close icon  allows the user view
the subtree.
A quick explaination of why we created an instance for John, but not for
the dog. Because the example references John only by name,
the two parties that are talking both know the
same John person. If the example sentence was more like This guy
named John bought a dog, the listener would assume this is a John
that he does not know. In this example, we would not have created an
instance beforehand, because the system does not know about the John. But
in our example, since only the name was used, the system will assume
the speaker is refering to a John that both the speaker and listener
already know.
Likewise for the dog, since the example said John has a dog, the
listener keys on the word a as saying this is a new dog that the listener
has no prior knowlegde of. If the example was John bought the dog,
the listener would assume that the speaker and listener had previously
spoken about a dog that John had been considering purchasing, and the
sentence simply confirms the information that John had actually purchaced
the dog in question. In this case, we would have created an instance
for the dog, becuase the system would have prior knowledge. The system
uses articles (a, an, and the) to either search for an existing instance,
or create a new one.
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