Technical item 2: SP -- was: Re: [Coin-standards] An argument for public domain modeling infrastructure

[Leonardo B. Lopes]

Once again I'm going to try to take the opportunity of having some really
experienced people around to throw some technical issues out there...

Dear Dr. King,

	Have you had a chance to look at the stage separation aspects of
the proposal I presented in Miami? I've since changed them a little,
moving the T definition to the child stage, which makes much more sense. I
can explain it to you if something doesn't make sense. I feel there are
two aspects there which are fundamental in the SP context:

	1) Sparse matrix inheritance. How did the SMPS authors arrive at
the definitions they chose? I had some trouble working with that mechanism
in my previous paper, so in my proposal I have a more sophisticated
inheritance scheme, equivalent to having possible more than one "core". As
far as the solver is concerned, of course, this should be transparent.

	2) I find it a lot easier to work with SP objects if the T, W, and
A matrices are explicitly denoted. The A matrix in my notation is the part
of the the W martix whose rows refer only to columns in the current stage.
Yet other than my own papers, I have only found that notation in a couple
of other places. I'd like to speculate that the reason for that is that a
lot of our notation was set up by solving two-period problems, in which
case the distinction is not very important. But maybe there is something
broken about doing things that way that I haven't seen yet. Does that seem
like a reasonable idea to you?

	Basically what I am asking, not only to Dr. King, but to any of
the other SPers who may be on this list, is to try to break the SP part of
the proposal that is on the web page, or come up with a completely
different initial design. I should warn that there is something currently
wrong with it (the stage of the T matrix), but I'll fix it if I find
someone who is willing to take a look at it and try and break it.

Thanks,
Leo.

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