[Coin-lpsolver] SOS in preprocessing

[jtyates at buffalo.edu]

I've spent some time recently looking into the presence and usage of SOS
as a form of preprocessing and branching within COIN.  The main files I
have found which contain SOS code are in CglPreProcess, CbcBranchActual
and in a sample code found under Cbc\Samples simply called SOS.cpp.

As of right now, I can see that Coin has the ability to find SOS and
branch on them.  What I still can't see is specifically how the
weighting of the SOS is accomplished and what the weights represent
(weightSOS_), whether the SOS branching in Cbc is based off of the
preprocess SOS found in the Cgl or whether these are two independent
steps, and whether there is much on SOS2 (from what I've seen it appears
that the focus is on SOS1 and the fixing and branching that comes from
it, and not so much on SOS2).

Any direction on where to find additional SOS code or materials within
any of the programs would be helpful.  Also, any answers to the above
questions on SOS would be sincerely appreciated.  I am specifically
interested in SOS as they relate to preprocessing.

Thank you,

Justin

__________________________________________
Mr. Justin .T. Yates
Dept. of Industrial and Systems Engineering
State University of New York at Buffalo
415 Lawrence D. Bell Hall
Buffalo, NY 14260-2050