Class Descriptions

There are attributes and there are class attributes.  An example of a statement that describes an attribute is "the bear is hungry."  It is true for the current bear under consideration.  A class attribute assignment, on the other hand, applies to all bears, like this: "bears are hungry."

Here's an example of the simple attribute:

>> the red bear is hungry
 the red bear is hungry.
>> is the brown bear hungry?
 maybe. I do not know.
>> is the white bear hungry?
 maybe. I do not know.
>> is a bear hungry?
 yes. the red bear is hungry.

Note that only the red bear is hungry. 

Here is an attribute assignment that applies to a whole class--the class of all bears:

>> bears are hungry
 bear are hungry.
>> is the red bear hungry?
 yes. the hungry bear is hungry.
>> is the brown bear hungry?
 yes. the hungry bear is hungry.
>> is the white bear hungry?
 yes. the hungry bear is hungry.
>> are bears hungry?
 yes. bear are hungry.

Class attributes can be overridden by simple attributes, like so:

>> bears are hungry
 bear are hungry.
>> the brown bear is not hungry
 the brown bear is not hungry.
>> is the red bear hungry?
 yes. the hungry bear is hungry.
>> is the white bear hungry?
 yes. the hungry bear is hungry.
>> is the brown bear hungry?
 no. the not hungry bear is brown.

Propositions can also apply to classes too, as in "bears like fish."

>> bears like fish
 bear like fish.
>> do red bears like fish
 yes. red bear like fish.
>> do white bears like fish?
 yes. white bear like fish.
>> do brown bears like fish?
 yes. brown bear like fish.

The signal that we are talking about a class description comes from the use of the plural for the subject.  When we say "bear is hungry" we are describing a particular bear.  When we say "bears are hungry" we are talking about all bears.  

In order to take advantage of class descriptions, the plural form of a noun (thing) has to be present in the vocabulary definition, and has to have a special designation of "plabel".  Here is the definition of "bear":

define  bear-n1
        plabel          bears
	    label           bear
        child-of        mammal-n1
        orthogonal      mammal-n1
        orthogonal      beartypes-n1

The "plabel" statement tells Brainhat that this label is a plural, and that when it is used in an attribute assignment or proposition it describes a class description that applies to all bears.

Any noun defined in "things.txt" (in the data subdirectory) can have a plabel (or two or three).  As of this writing, only a couple definitions do--bears and bananas.  You may modify other definitions as you wish for experimentation.