On Mon, November 19, 2012 16:44, Edward Barkmeyer wrote:
> 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.
>
> 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. (01)
By asking for more capability, the industry uses are -- without knowing it --
asking for more expressiveness. (02)
> Performance is the returning of answers in a reasonable length of time. (03)
I note that performance is a scale, not a binary relation. It revolves
around the quality of the answer as well as the amount of time it
takes to provide it. Within reason, a user (industry or other) would
be willing to trade off some time for a higher quality answer. (04)
> Amanda Vizedom wrote:
> ...
>> 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. (05)
> Of course. But the line between DLs and FOLs *is* a sweet spot for
> this. (06)
Ed, i almost always agree with you 95+% of the time, but i beg to
differ here. No business programmer programs in a DL language,
from COBOL onward. (07)
> 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. (08)
I note that a FOL can compute whatever a DL can compute in the same
amount of time. So, how could a FOL be worse? (09)
If programmed well, an FOL can compute far more calculations efficiently
than a DL can compute at all. Note that the limitations on FOL are for
the most extreme situations. It does not mean that any reasoning in
the FOL will be undecidable. (010)
I remember a case in an algorithm's class where an inefficient order N
algorithm was deemed "better" than an efficient NP algorithm. However,
the complexity of the input necessary before the number of calculations
curves crossed made this crossing point at over 10^105 calculations.
I argued that the higher-order algorithm was "better" as no inputs
given to both algorithms would come out with an answer first from
the polynomial algorithm within the lifetime of the poser (or the poser's
machine, or the poser's nation). (011)
-- doug f (012)
>> 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. (013)
> 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.
>
> -Ed
>
>>
>> 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]
>>
>
>
> --
> 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
>
> "The opinions expressed above do not reflect consensus of NIST,
> and have not been reviewed by any Government authority."
>
>
>
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