[Coin-discuss] Re: A query on Special Ordered Sets in Cbc

[John J Forrest]

Robin passed on this query and I thought I would reply here.
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Robin,

Does CBC contain support for special ordered sets? If so, where can I find 
more information about it? Can I also use this feature with the command 
line version of CBC, or only with the API?
Thanks,

Segev Wasserkrug

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An example of using special ordered sets of type 1 with the API is in 
Cbc/Samples/sos.cpp.  This can also be compiled to give an artificial 
example of using SOS of type 2.  They do work effectively on suitable 
problems and I have been informed by John Tomlin (what does he know about 
SOS? :-) that the SOS 2 feature works well on genuine problems.

As a reminder the recommended version of command line CBC is Cbc/solve 
(created by "make solve").  The default preprocessing is to try and 
identify SOS of type 1, however it is over cautious in doing this.  If 
there is interest I could think of allowing solve to read an SOS file 
although there is a problem of what to do if preprocessing makes large 
changes to the model.

John Forrest
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