[Coin-standards] INFORMS / directions

[Leonardo B Lopes]

Hi Laurent,

	Thanks for contributing some thoughts. Will you be at San Jose? One quick 
question: at which point are you saving your models? Irv had a good 
example of the difference between model and instance which I will repeat 
here (forgive my linear example):

Model:
	sum_{i \in I} x_i = b

Instance:
	x_1 + x_2 + x_3 + x_4 + x_5 + x_6 + x_7 + x_8 + x_9 + x_10 = 3

Which of these two objects are you representing?

A clarification:

	- We are not necessarily trying to linearlize CP. What we are looking to 
do is exactly what you describe, adding constructs for cumulative, or 
all_different, etc... in an efficient manner.

Thanks for your input.


> 
> 
> Hello, 
> 
> First of all, I would like to apologize about my lack on visible work on
> this subject.
> 
> Let me present myself, I am Laurent Perron and I am project leader of
> ILOG Solver and ILOG Concert. ILOG Concert is a common modeling API
> shared by ILOG Cplex and ILOG Solver (our CP engine).
> 
> The main idea behind an XML format suitable for CLP or CP is about
> expressiveness. For instance, we have some "logical" constraint that we
> use to model our problem. Such logical constraints are "all different",
> "sequence". They may be very difficult to linearize, or impossible to
> linearize. They may also have different linearizations that adapted to
> different situations.
> 
> Therefore, the implication is that for each of these logical
> constraints, there will be a special xml tag for them.
> 
> Please note that our CP engine deals with other kind of basic objects
> (integer set variable, integer bag (or multi-set) variables). There are
> also extensions to deal with scheduling, dispatching and routing,
> configuration... Each of these extensions introduce new basic objects
> and thus new XML tags.
> 
> We have also developed a internal XML layer to save out models. This
> layer is mapped quite directly from our Concert layer. I think it would
> be a good idea to show some samples of these generated XML to compare
> with this standardization effort (that we want to support in addition to
> this simple XML format).
> 
> --Laurent Perron
> 
> 
> 
> 
> 
>>  * I have not thought about complementarity. How should we represent 
>>that class of problems? Suggestions? How about MDPs? Distributions 
>>problems? etc...?
>>
>>  * Other items?
>>
>>
>>Thanks,
>>Leo.
>>--
>>=======================================================================
>>Leonardo B. Lopes                                      leo at iems.nwu.edu
>>Ph.D. Candidate                                           (847)491-8470
>>IEMS - Northwestern University             http://www.iems.nwu.edu/~leo
>>
>>
>>
>>
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> 
> 


-- 
=======================================================================
Leonardo B. Lopes                                      leo at iems.nwu.edu
Ph.D. Candidate                                           (847)491-8470
IEMS - Northwestern University             http://www.iems.nwu.edu/~leo