<br><font size=2 face="sans-serif">Most modeling languages allow one to
perform iterative </font>
<br><font size=2 face="sans-serif">and conditional operations. But
sometimes the solver </font>
<br><font size=2 face="sans-serif">needs a great deal of interaction with
the model. </font>
<br><font size=2 face="sans-serif"> </font>
<br><font size=2 face="sans-serif">Simulation based solvers, like those
used in stochastic</font>
<br><font size=2 face="sans-serif">programming, need a *lot* of interaction.
My interest in </font>
<br><font size=2 face="sans-serif">richer standards, like XML, derives
from the potential for </font>
<br><font size=2 face="sans-serif">a solver to be able to parse a model
object once </font>
<br><font size=2 face="sans-serif">and then optimize the subsequent interactions
with the </font>
<br><font size=2 face="sans-serif">model object in the course of the solution.</font>
<br>
<br><font size=2 face="sans-serif">However, it doesn't seem interesting
(to me at least)</font>
<br><font size=2 face="sans-serif">to have an XML version of the matrix-objective-rhs
format.</font>
<br><font size=2 face="sans-serif">MPS does this just fine. Moreover
MPS can easily be </font>
<br><font size=2 face="sans-serif">extended to cover any sort of property
that one could place</font>
<br><font size=2 face="sans-serif">on matrix, objective, or right-hand-side
entries. We have </font>
<br><font size=2 face="sans-serif">even extended MPS to express stochastic
data entries.</font>
<br>
<br><font size=2 face="sans-serif">XML is much better suited to express
information about</font>
<br><font size=2 face="sans-serif">how model entities are connected. This
information</font>
<br><font size=2 face="sans-serif">could be very useful for simulation-based
solvers -- </font>
<br><font size=2 face="sans-serif">the solver could extract the "tree"
of model entities that </font>
<br><font size=2 face="sans-serif">have to be updated when an entity is
simulated. </font>
<br>
<br><font size=2 face="sans-serif">I believe that similar observations
can be made for</font>
<br><font size=2 face="sans-serif">non-linear solvers as well.</font>
<br>
<br><font size=2 face="sans-serif">Alan<br>
</font>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td width=40%><font size=1 face="sans-serif"><b>Matthew Galati <Matthew.Galati@sas.com></b>
</font>
<br><font size=1 face="sans-serif">Sent by: coin-discuss-bounces@list.coin-or.org</font>
<p><font size=1 face="sans-serif">11/20/2007 04:12 PM</font>
<table border>
<tr valign=top>
<td bgcolor=white>
<div align=center><font size=1 face="sans-serif">Please respond to<br>
Discussions about open source software for Operations Research
<coin-discuss@list.coin-or.org></font></div></table>
<br>
<td width=59%>
<table width=100%>
<tr valign=top>
<td>
<div align=right><font size=1 face="sans-serif">To</font></div>
<td><font size=1 face="sans-serif">Discussions about open source software
for Operations Research <coin-discuss@list.coin-or.org></font>
<tr valign=top>
<td>
<div align=right><font size=1 face="sans-serif">cc</font></div>
<td><font size=1 face="sans-serif">Rob Pratt <Rob.Pratt@sas.com></font>
<tr valign=top>
<td>
<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td><font size=1 face="sans-serif">RE: [Coin-discuss] Open-source Modeling
Languages</font></table>
<br>
<table>
<tr valign=top>
<td>
<td></table>
<br></table>
<br>
<br>
<br><tt><font size=2>FYI. I know this is a discussion about OpenSource
languages.<br>
<br>
But, what you describe below can be easily done with SAS/ORs OPTMODEL language.
By declaring non-static index sets, parameters, etc. you can easily modify
the model components based on some output in some loop. I don't know about
other vendors - but, I suspect it should be possible.<br>
<br>
-----Original Message-----<br>
From: coin-discuss-bounces@list.coin-or.org [mailto:coin-discuss-bounces@list.coin-or.org]
On Behalf Of Michael Hennebry<br>
Sent: Tuesday, November 20, 2007 3:46 PM<br>
To: Discussions about open source software for Operations Research<br>
Subject: Re: [Coin-discuss] Open-source Modeling Languages<br>
<br>
On Tue, 20 Nov 2007, Brian Borchers wrote:<br>
<br>
> First, although many normal users produce models using a modeling<br>
> language like AMPL, many other other users produce their problem<br>
> instances using conventional programming languages like C.<br>
<br>
Yup. Some of us write programs that do things like this:<br>
read data<br>
generate problem<br>
while(1) {<br>
solve problem<br>
if done break<br>
use solve output to edit problem<br>
}<br>
print result<br>
<br>
The edit problem part can be hard with modeling language.<br>
<br>
--<br>
Mike hennebry@web.cs.ndsu.NoDak.edu<br>
"Horse guts never lie." -- Cherek Bear-Shoulders<br>
<br>
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