[Cbc] Fwd: SOS gramar for LP file for CBC

[Stefan Vigerske]

Hi,

the .lp reader code is in CoinUtils/src/CoinLpIO.*, see
https://projects.coin-or.org/CoinUtils/browser/stable/2.8/CoinUtils/src/CoinLpIO.hpp
https://projects.coin-or.org/CoinUtils/browser/stable/2.8/CoinUtils/src/CoinLpIO.cpp

I don't see any support for SOS there, so I would say that there is no 
SOS support for .lp files in Cbc, yet.

Stefan

Am 18.05.2012 21:23, schrieb Andres Sommerhoff:
> Hello, somebody knows how do you use SOS with a LP format file read by CBC?
>
> I have tried several form of SOS grammatics, but CBC fails to interpret the
> LP file. For example, if I use the following simplified LP file:
>
> MINIMIZE
> Obj: +1000 A1 +1200 A2 +1500 A3 +1200 B1 +1300 B2 +1400 B3 +1100 C1 +1200
> C2 +1300 C3
> SUBJECT TO
>   //+1 A1 +1 A2 +1 A3 = 1  //Should not be necessary if using SOS, I have
> tried this without comments also.
>   //+1 B1 +1 B2 +1 B3 = 1  //Should not be necessary if using SOS, I have
> tried this without comments also.
>   //+1 C1 +1 C2 +1 C3 = 1 //Should not be necessary if using SOS, I have
> tried this without comments also.
>   +10 A1 +15 B1 +3 C1>= 3
>   +10 A2 +15 B2 +3 C2>= 10
>   +10 A3 +15 B3 +3 C3>= 3
>   +10 A1 +15 B1 +3 C1<= 15
>   +10 A2 +15 B2 +3 C2<= 15
>   +10 A3 +15 B3 +3 C3<= 15
> BINARY
>   A1 A2 A3 B1 B2 B3 C1 C2 C3
> SOS
>   set1: S1::  A1 A2 A3
>   set2: S1::  B1 B2 B3
>   set3: S1::  C1 C2 C3
> END
>
> However, I get the following when trying to read the previous LP file:
>
> Coin3007W ### CoinLpIO::readLp(): Binary variable SOS does not appear in
> objective function or constraints
> Coin3007W ### CoinLpIO::readLp(): Binary variable set1: does not appear in
> objective function or constraints
> Coin3007W ### CoinLpIO::readLp(): Binary variable S1:: does not appear in
> objective function or constraints
> Coin3007W ### CoinLpIO::readLp(): Binary variable set2: does not appear in
> objective function or constraints
> Coin3007W ### CoinLpIO::readLp(): Binary variable set3: does not appear in
> objective function or constraints
> Coin3007W ### CoinLpIO::is_invalid_name(): Name set1: contains illegal
> character ':'
> Coin3007W ### CoinLpIO::are_invalid_names(): Invalid name: vnames[10]: set1:
> Coin3007W ### CoinLpIO::is_invalid_name(): Name S1:: contains illegal
> character ':'
> Coin3007W ### CoinLpIO::are_invalid_names(): Invalid name: vnames[11]: S1::
> Coin3007W ### CoinLpIO::is_invalid_name(): Name set2: contains illegal
> character ':'
> Coin3007W ### CoinLpIO::are_invalid_names(): Invalid name: vnames[12]: set2:
> Coin3007W ### CoinLpIO::is_invalid_name(): Name set3: contains illegal
> character ':'
> Coin3007W ### CoinLpIO::are_invalid_names(): Invalid name: vnames[13]: set3:
> Coin3007W ### CoinLpIO::readLp(): Invalid column names
>
>
> I have tried also other forms of SOS but no good results. Unfortunately,
> I'm fix to LP (because I'm using OpenSolver for Excel) without chances for
> using MPS format (that I have seen few CBC examples of SOS for MPS).
>
> Somebody knows what is the correct grammar for SOS with LP files in
> coin-OR? Where is the c++ **source** file where an LP file is processed? (I
> have searched it but unsuccessfully)
>
> I will appreciate if anybody can give me a hand on this. Thank you in
> advance.
>
> Best regards,
> Andres Sommerhoff
>
> PS: I have tried with CBC version 2.7.1 and 2.7.5 compiled for windows.
>
>
>
>
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-- 
Stefan Vigerske
Humboldt University Berlin, Numerical Mathematics
http://www.math.hu-berlin.de/~stefan