Re: Mesozoic-ware

[Dinogeorge@aol.com]

In a message dated 96-01-13 20:51:33 EST, pharrinj@PLU.edu writes:

>> At 02:45 AM 1/13/96 -0500, Nicholas R. Longrich wrote:
>
>> >Birds are dinosaurs, so does the commutative property (A=B, B=C, so
>> >A=C) apply here and make them reptiles?

Minor point--this is not commutativity; it is the transitive property of
equality. Commutativity is the property that a+b = b+a, where "+" denotes any
commutative operator. Addition and multiplication are commutative, but
subtraction and division are not.

Another minor point--equality isn't the right operation to use here. You are
talking about nested set inclusion: A [Reptilia] contains B [Dinosauria], and
B [Dinosauria] contains C [Aves], therefore A [Reptilia] contains C [Aves].