Re: [ontolog-forum] Fwd: Ontolog invited speaker session - Dr. Mark Greaves on the Halo Project - Thu 2008.06.19

Hi Chimeze --

You wrote:

*Negation as failure can be validly used to infer from a failure if the data
is controlled (which is especially the case with well-designed experiments
where it would be irresponsible to to do otherwise).*

Agreed.

Another aspect is to use executable English descriptions of predicates [1]
that depend on NAF.

Then, an answer can be of the form "Based on the data available up to
20080626...", and it can be explained in English too.

                                         Cheers,  -- Adrian

[1]  Internet Business Logic
A Wiki and SOA Endpoint for Executable Open Vocabulary English over SQL and
RDF
Online at www.reengineeringllc.com    Shared use is free

Adrian Walker
Reengineering



On Thu, Jun 26, 2008 at 4:05 PM, Chimezie Ogbuji <ogbujic@ccf.org> wrote:

>  Just a quick comment.  Pat H. wrote
>
> [[
> The basic snag with negation as failure is that it is almost always* not
> valid*. It is simply* wrong*. The cases where you can validly infer, from
> a failure to prove P, that P is false, are extremely rare. They only occur
> in specialized circumstances in specialized tasks performed by specialists
> in certain limited cases.
> ]]
>
> I would disagree about this case being the exception.  Negation as failure
> can be validly used to infer from a failure if the data is controlled (which
> is especially the case with well-designed experiments where it would be
> irresponsible to to do otherwise).  If a clearly-defined protocol is used as
> part of the data collection process (for example, only assert P if P is *
> known*), then you can make valid inferences about missing content without
> the burden of classic negation, which requires a significant amount of
> effort (either having a large amounts of assertions about class
> disjointedness, etc. or requiring explicit assertions about the absence of
> data) to ensure that you can *prove*  that P is false.
>
>
> On 6/25/08 11:06 PM, "Pat Hayes" <phayes@ihmc.us> wrote:
>
> At 8:37 PM -0400 6/25/08, Adrian Walker wrote:
>
> Hi John --
>
>
> Allow me to respond also.
>
> You wrote...
>
> *It's important for us to develop Common Logic as the growth path
> for ontologies and to incorporate CL in the Semantic MediaWiki.
>
> Anything currently represented in either the Semantic Web notations
> or relational databases can be mapped to Common Logic.  And the
> more compact CL notation is vastly more efficient in storage space,
> transmission time, and computation time than the current Semantic
> Web notations.
>
> We should position CL as the foundation for Semantic Web 3.0.
> *
> You may like therefore to address Chris Welty's point that CL appears
> infeasible for the W3C rule interchange project.  In slide 11 of [1], Chris
> says:
>
> *The CL and IKL approach [is] deprecated: infeasible for this group [W3C
> Rule Interchange], as major differences appeared irreconcilable (e.g.
> non-mon vs. mon)
> *
>
>
> He is there referring to a particular* approach*, viz. to adopt a highly
> expressive language into which all rule languages can be translated, which
> was used in the IKRIS project which produced IKL. If however you read on in
> the same slides, you will find that the language finally adopted as the
> initial Rule standard, though much weaker than CL, in fact is a classical
> logic with a classical negation, just like negation in every other logic
> with a clear semantics.
>
> The fundamental difficulty seems to be
>
>
> That isnt the* fundamental* difficulty for RIF.
>
> that CL and IKL have chosen a theoretical semantics for negation
>
>
> Its not especially 'theoretical'. It is simply what negation means in
> ordinary language. If you say cows are white, and I say, No, cows are brown;
> then my "no" says that what you said is false. That simply is what negation
> * means*. This is a common-sense, pre-theoretical notion of negation.
> So-called 'negation as failure' is the theoretical notion, and it only
> arises from database theory. The basic snag with negation as failure is that
> it is almost always* not valid*. It is simply* wrong*. The cases where you
> can validly infer, from a failure to prove P, that P is false, are extremely
> rare. They only occur in specialized circumstances in specialized tasks
> performed by specialists in certain limited cases. Can you prove that every
> finite abelian group can be expressed as the direct sum of cyclic subgroups
> of prime-power order? Answer quickly. Suppose, just for the sake of
> argument, that you can't. Are you justified in concluding that this is
> false? Maybe you had better hedge your bets.
>
> from before the computer era, whereas SQL and most logic based programming
> languages use a different meaning for negation -- one that can also be
> formalized, e.g. as in [2].
>
>
> It can be formalized, for sure. It can in fact be formalized in many
> different, incompatible, ways. All of them however make it vividly clear
> that this is not a generally correct inference rule.
>
> Pat
>
>
> Thanks for your thought about this.
>
>                                        -- Adrian
> [1]
> http://ontolog.cim3.net/file/resource/presentation/ChrisWelty_20080612/W3C-Rules-Interchange-Format--ChrisWelty_20080612.ppt
> <http://ontolog.cim3.net/file/resource/presentation/ChrisWelty_20080612/W3C-Rules-Interchange-Format--ChrisWelty_20080612.ppt><http://ontolog.cim3.net/file/resource/presentation/ChrisWelty_20080612/W3C-Rules-Interchange-Format--ChrisWelty_20080612.ppt>
>
> [2]  Backchain Iteration: Towards a Practical Inference Method that is
> Simple
>   Enough to be Proved Terminating, Sound and Complete. Journal of Automated
> Reasoning, 11:1-22
>
> Internet Business Logic
> A Wiki and SOA Endpoint for Executable Open Vocabulary English over SQL and
> RDF
> Online at www.reengineeringllc.com <http://www.reengineeringllc.com><http://www.reengineeringllc.com>    Shared use is free
>
> Adrian Walker
> Reengineering
>
>
>
>
> On Mon, Jun 23, 2008 at 10:54 PM, John F. Sowa <sowa@bestweb.net> wrote:
>
>
> Peter,
>
> Thanks for posting the audio for Mark Greaves talk.  I wasn't
> able to log in for the talk, but I read the slides.  The audio
> covers some important points that are not in the slides:
>
> http://ontolog.cim3.net/cgi-bin/wiki.pl?ConferenceCall_2008_06_19
>
> The Semantic MediaWiki is very important work, and since it is
> available as open source, we should use it.
>
> But one important point that Mark mentioned is that the reasoning
> capabilities of current Semantic Web technology is very weak.
> RDF(S), OWL, SPARQL, and RuleML are useful, but weak subsets
> of Common Logic.
>
> It's important for us to develop Common Logic as the growth path
> for ontologies and to incorporate CL in the Semantic MediaWiki.
>
> Anything currently represented in either the Semantic Web notations
> or relational databases can be mapped to Common Logic.  And the
> more compact CL notation is vastly more efficient in storage space,
> transmission time, and computation time than the current Semantic
> Web notations.
>
> We should position CL as the foundation for Semantic Web 3.0.
>
> John
>
>
>
>
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