I think Amanda is right about getting lost in the academic descriptions
of the properties of reasoners and languages. I phrased my concerns
inappropriately, it seems. (01)
John Sowa originally wrote that no user asks for decidability, users
always ask for more expressiveness. I have yet to hear a user ask for
either. Industry users are interested in capability and performance.
They ask for more capability, but they want a guarantee of performance.
"Capability" is the combination of an expressive language for axioms and
questions and the availability of a reasoning tool that uses them to
return answers. Performance is the returning of answers in a reasonable
length of time. (02)
Amanda Vizedom wrote: (03)
> The real valuable work comes from identifying logic languages and
> procedures, that maximize expressiveness, usability, and reasoning
> within the domain of statements and tasks the user needs. That is more
> complex and subtle. (04)
Exactly. (05)
> There are lots of ways to design systems to either disallow certain
> statements (IMHO, better done semantically than
> via unusably counter-intuitive or restricted syntax), or decline to
> process certain reasoning patters that have a high rabbit-hole risk,
> or cut out after a certain time, or use other techniques to tune
> performance. The line between decidable and undecidable systems is not
> a sweet spot for this. (06)
Of course. But the line between DLs and FOLs *is* a sweet spot for
this. There are many industry applications that can be met by DLs with
their measurable performance, in spite of the fact that their
expressiveness is limited and some of the axiom formulations are hard
for human experts to read. The land of FOLs is significantly more
expressive, but it has many more cliffs and sinkholes that make it much
more difficult to predict performance. (07)
> For all of these reasons, IMHO, decidability is a red herring. Worse,
> and to mix my metaphors, it is a red herring that has led far too many
> talented people on a wild goose chase when they could be doing much
> more useful work to advance the state of the science and technology in
> really valuable ways. (08)
I'm not so sure that academic pursuits like decidability actually lead
talented people away from useful work. We have a rule that a Ph.D. has
to advance the state of the art. It means that to get a Ph.D from a
prestigious institution will require you to do a few years work in some
esoteric field like decidability. In the course of that work, you will
learn what all the academic terminology means, how the concept space is
related, and what the state of the art actually is. When you have the
degree, you can start doing "useful" things, that use some parts of the
knowledge you gained, and the skills you gained in comprehending
ill-written technical literature. It is unlikely that you will have a
direct application for what you know about decidability, but it is
equally unlikely that a talented mathematician will find an industry
application for counting graphs or proving the convergence of Sobolev
methods, or that a botanist will find industry application for isolating
cabbage genomes. The loss only occurs when the talented student isn't
prepared for the fact that industry is more interested in what else s/he
knows, and continues looking for interest in his/her academic
specialty. The purely academic pursuit is part of the rite of passage,
and the maintenance of expertise in it may later be important in guiding
others. The truly talented people will find useful things to do; the
others are just intellectually gifted. It takes most of us a long time
to understand what knowledge we really have and what its value is. Some
of the gifted never do. (09)
-Ed (010)
>
> Best,
>
> Amanda
>
> On Mon, Nov 19, 2012 at 1:52 PM, Ed Barkmeyer <edbark@xxxxxxxx
> <mailto:edbark@xxxxxxxx>> wrote:
>
>
> [snip]
> Everyone agrees that FOL is more expressive and potentially more
> useful,
> but all of the reasoning procedures that are widely used in academia
> either restrict the allowable FOL inputs in some way that greatly
> reduces its expressiveness or are programmed to throw up their
> hands at
> some point -- they "halt" by saying "not determinable" (in some
> language). The problem of not knowing the relationship between input
> data -- the sets of valid sentences -- and the "not determinable"
> result
> is what causes industry to shy away from FOL reasoners.
> [sniip]
> (011)
--
Edward J. Barkmeyer Email: edbark@xxxxxxxx
National Institute of Standards & Technology
Systems Integration Division, Engineering Laboratory
100 Bureau Drive, Stop 8263 Tel: +1 301-975-3528
Gaithersburg, MD 20899-8263 Cel: +1 240-672-5800 (012)
"The opinions expressed above do not reflect consensus of NIST,
and have not been reviewed by any Government authority." (013)
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