[Coin-SMI] Re: Re: Changing right hand side of inequalities

[Alan King]

Classes derived from the base class SmiCoreCombineRule define how core and 
scenario data are to be combined when the deterministic equivalent is 
generated.   It is quite simple to grep the code and see where and why 
these classes are invoked. 

Rather than continue to debate the SMPS standard -- going on for almost 20 
years now  -- I decided it would be better if users could provide their 
own rule to readSmps().  For example, a user could decide to use 
multiplication as the basic combination operation just by providing the 
appropriate SmiCoreCombineRule class.  An example of this pattern is used 
to read Francois' bug example in Coin/Examples/Stoch/stoch.cpp.

On the other hand, an energetic person could take the responsibility to 
develop a workable community concensus for the SMPS standard and write the 
appropriate SmiCoreCombineRule classes.

Alan



Francois Margot <fmargot at andrew.cmu.edu> 
Sent by: coin-smi-bounces at list.coin-or.org
05/30/2005 09:59 AM

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Subject
Re: [Coin-SMI] Re: Re: Changing right hand side of inequalities







>
> SMPS is silent on these points.  So is, for that matter, MPS.  It is a
> fundamental ambiguity built into the standard.
> In the case of the direct interface, nothing needs to be documented at
> all.  It will always do what the user intends.
>

It is ambiguous only if you assume that inequalities are defined with a 
lower 
and an upper bound (i.e. ranged constraints). Otherwise, the rhs is one
of the two and any request to change the rhs is unambiguous. Since MPS
files require that each inequality is identified as a "<=", ">=" or "="
constraint, I would consider that changing the rhs of such a constraint 
means changing the value of the rhs without changing the type of the 
inequality. Only for ranged constraints (that are indeed allowed to appear 

in a MPS file), the request is ambiguous.

In any case, all this is just bickering. My point is that the actual 
implementation of readSmps() could be improved to be able to model
a larger class of problems using core, stoch and time files.

>
> As we have said, SMI does handle inequalities.  The example you
> provided is easy and natural to code in the direct interface.  The
> issue is how SMPS should handle inequalities in input files.

I understand that the problem is in readSmps(). I want to improve it,
no work around will make me happy.

Francois
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