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From: brucec%phoebus.phoebus.labs.tek.com@RELAY.CS. (Bruce Cohen;;50-662;LP=A;)
Newsgroups: sci.virtual-worlds
Subject: Re: Who says what to whom (was Re: VR Protocols.)
Message-ID: <7661@milton.u.washington.edu>
Date: 16 Sep 90 19:42:22 GMT
References: <31304@unix.cis.pitt.edu> <7507@milton.u.washington.edu> <7569@milto
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In article <7569@milton.u.washington.edu> wex@dali.pws.bull.com (Buckaroo Banzai
) writes:
    [I wrote:]
>       If the possible number of optional attributes is
>       large, the number of such emulation strategies can also be large, and
>       that's where this scheme can break down.
> 
> Number of strategies?  I'd be hard-pressed to come up with *one* general
> strategy.

Sorry, I wasn't clear there: by strategy, I meant a per-attribute strategy
for emulating that attribute using some set of other attributes.  For
instance, in graphics texture is frequently emulated with crosshatching or
some other regular pattern.

> 
> OK - the idea was not to have each object have KR frames, but to have there
> be a system of knowledge about the world to which all objects could refer.
> That is, if I'm a ball object and I'm about to impinge on a bat object, I
> know that this object is of type T (or one of its subclasses) and I know
> where to look in the knowledge net for information about objects like that.
> Once I've inferred some things about this type of object, I can construct a
> request of the bat.
> 
> The idea of this sort of implementation is to prevent what is essentially
> "real-world" knowledge from having to be part of objects' structures and
> also to avoid having objects know too much about how other objects are
> implemented.
> 

I'm still a little hazy on this, so let me try to rephrase it and correct
me if I'm wrong.  I think you are saying that the frames contain (inter
alia) knowledge of the attributes valid to some sublattice of the object
inheritance graph, and that an object (the baseball, say) wanting to
negotiate attributes with another object (the bat) can find the
intersection of the attribute lists in the ball's frame and the bat's
frame.

If this is what you are saying, how is this different from each object
having the ability to emit its attribute list on request?  There still has
to be a computation somewhere which determines how to map the things the
ball can do to the things the bat wants to do to it; where is this done?

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Bruce Cohen, Computer Research Lab        email: brucec@tekcrl.labs.tek.com
Tektronix Laboratories, Tektronix, Inc.                phone: (503)627-5241
M/S 50-662, P.O. Box 500, Beaverton, OR  97077