[Coin-standards] An argument for public domain modeling infrastructure

[Irv Lustig]

Leo:

At 12:45 PM 4/11/02 -0500, Leonardo B. Lopes wrote:
>On Thu, 11 Apr 2002, Alan King wrote:
>
>It is interesting that this idea of a modeling standard keeps coming up
>over and over again. That is not what I see as the outcome of this work.

Maybe it *should* be?????

>It would be nice if we had that, but I don't even think it is possible to
>develop a standard for modeling. This, BTW, is my opinion and I don't even
>know if my advisor agrees with it. And a standard that can be modified by
>vendors (like what Irv proposed) is not a standard at all.

What I suggested is a standard modeling language that is controlled by some 
kind of standards "organization".  Modifications to the language go through 
this organization.  There is a reference implementation of the language 
that is publicly available.  Vendors can use (license???) this reference 
implementation, or create one of their own.  So you have a standard, 
defined as the language itself.

Java works this way.  The vendors are free to write their own JVM's, and 
there is a reference implementation that Sun will license to other vendors.

>  Maybe a lot of
>vendors wish that the ampl and gams licensing terms were different; that
>is reasonable, but to me that is a separate issue from this one.

I don't think it is licensing terms that are the barrier here.  It is 
simply that there is a competitive market with a bunch of modeling 
languages.  There is one language, AMPL, that is used a lot in academia and 
somewhat in industry.  But AMPL has problems when you try to build an 
application around it.  And the implementation of AMPL is understood by one 
individual.  If he gets hit by a Mack truck, the future of AMPL is 
uncertain.  So the vendors (ILOG with OPL, Maximal with MPL, Dash with 
Mosel, Lindo with Lindo) have created new languages that get around this 
problem. We all compete in this market.  It is that competition that 
stifles the creation of a standard.

>I like the idea of a modeling infrastructure. That is different than a
>modeling standard. This is what I feel we are trying to set up. A standard
>*for instances* is part of the foundation for that infrastructure. It
>allows a developer to use a modeling language or library for what they are
>good at; then manipulate the generated objects, send them to solvers, use
>integration tools, or whatever the situation demands.

If you were to rewind the clock 12 years to when AMPL was being created, 
then I could see creating a standard for instances in conjunction with the 
creation of AMPL.  But in today's world, the standard for instances doesn't 
solve any problem.


>Clearly it is not a reasonable pace of progress. There are lots of reasons
>for it, though. Maybe progress in modeling languages is more of a symptom
>than a cause. BTW, Soon we will have some workable implementations for SP
>coming out, from Mitra's group, and one that I am myself working on (when
>I'm not writing these emails:)).

The slow pace of progress in adding new features to modeling languages is 
mostly due to poor implementations and poor design of the languages.  You 
need to design a modeling language that has extensibility along with an 
implementation that supports extensions.  And from what I hear from people 
who have worked on this, it is really hard to design and implement such 
languages (modeling or otherwise).

         -Irv