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Re: [ontolog-forum] Current Semantic Web Layer pizza (was ckae)

To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Randall R Schulz <rschulz@xxxxxxxxx>
Date: Sun, 16 Sep 2007 17:11:57 -0700
Message-id: <200709161711.57200.rschulz@xxxxxxxxx>
On Sunday 16 September 2007 16:32, Mills Davis wrote:
> Randall,
>
> ...
>
> 3.  But, another issue that is nagging me is concerns the advantages
> of logical symmetry and sequence neutrality. Why is a processing
> distinction made between forward and backward axioms? Wouldn't the
> impact of all possible informational variables be (pre)computable at
> the time the backward/forward axiom was formulated? I guess what I'm
> probing is the notion of symmetry of expression.  If we view
> knowledge as a constraint space of conditional and unconditional
> expressions (rational paths) containing both dependent and
> independent variables, then isn't it possible to reason over the same
> mesh by changing what we consider independent and dependent, and thus
> address different types of questions? For example, I see this idea
> coming up recently in the discussion of "continuous search" and
> "perpetual analytics.."    (01)

The burden of deciding whether pre-computed consequences are 
advantageous is placed upon the knowledge engineer. Surely it would be 
better to have the system make that determination, but at this point 
(*), that is not a practical, feasible or possible computation.    (02)

In essence, this is a pragmatic distinction that Cyc foists upon the 
knowledge engineer.    (03)

However, a key fact to keep in mind is that the "forward" vs. "backward" 
distinction does not influence the inferential capabilities of Cyc nor 
the logic it implements (**). It is purely a performance issue. (In 
fact, a classic space vs. time tradeoff.)    (04)

(*) I have not used Cyc since about 2001. I cannot actually represent 
this as the current state of affairs in the Cyc knowledge 
representation and inference system in 2007.    (05)

(**) Whatever that may be...    (06)


As a software engineer, this is a reasonable approach to practical 
system optimization. As a knowledge engineer, it's an unwanted 
intrusion of the implementation realm into the knowledge representation 
realm.    (07)


> Mills    (08)


Randall Schulz    (09)

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