Re: Is a Cow an Animal?

[Matthias Felleisen <matthias@ccs.neu.edu>]

MrSpidey never scaled to classes, and doesn't even do a good job on the
structure hierarchy. When MrFlow comes on line, we will see what we can 
do for this. 

In the meantime, I would like to say that 

 class animal
   Stuff eat(Nothing in) ...
 end

is my favorite solution. Considering that in is in a negative position, it
is not surprising that we need to say there is Nothing that all animals eat. 
Somewhere in there is a universal quantifier, and somewhere else there is
an existential (or negated forall really), and that is what seems to be
going on. 

Given that, we have a food hierarchy of 

    Nothing
      /\
  Meat  Grass	[Texas version]

And the rest works out. 

-- Matthias