[Cbc] [cbc] SOS and Semis availability in release branch.

[John Forrest]

Richi,

There should not be any issues with using features in parallel.

The developments with SOS etc all took place during the 70's mainly at 
the consultancy company - Scicon.  Those were the days when a company 
could write optimization software mainly to be used for its clients. 
LP/IP codes included - Alligator (great name derived from a technique 
akin to linear programming - very bad code), Umpire (Unified 
Mathematical Programming incorporating refinements and extensions - very 
good code) and Sciconic (boring name).

You may find papers mostly authored by Martin Beale (you may also find 
Tomlin and Forrest in some of them).  They all involve very simple 
branching techniques to model increasingly complex ideas - so Linked 
Ordered Sets can directly model x*f(y).  A lot of these are in Cbc and 
it is easy for any user to extend them - Open Source can bring back some 
of the links between algorithm and application/customer.

Find some of the papers, but you may find it easier to get clear in your 
mind what techniques you would like to exist and then pose questions in 
this forum to help other people.

John

On 29/01/18 16:47, richi arora wrote:
> Hi John
>
> I tried sos and semi-continuous variables in trunk. It works fine for 
> the tests that I did.
> Thanks for taking the task up and providing the implementation for lp 
> files.
>
> Any plans when same might be available in a release ?
>
> However I was eager to know about:
> -> If you can point me to any tutorial/book that can tell best way to 
> use semi variables and SOS variables to get best performance. (PS: I 
> was till now using binary variables but performance took a hit)
> -> Are there in issues if I use semis or sos along with parallelizing 
> feature of cbc ?
>
> I plan to use parallelizing feature to improve performance.
>
> Thanks
> Richi Arora
>
>
> On Friday 19 January 2018, 11:01:48 PM IST, richi arora 
> <richi_arora_ra at yahoo.co.in> wrote:
>
>
> ah ok.
>
> Any link or info as in how can I use SOS or Lotsize in lp file ?
>
> I tried sos but still cbc crashed eg:
>
> min: -x1 -x2 -3 x3 -2 x4 -2 x5;
> c1: -x1 -x2 +x3 +x4 <= 30;
> c2: +x1 +x3 -3 x4 <= 30;
> x1 <= 40;
> x2 <= 1;
> x5 <= 1;
>
> sos
> SOS1: x1, x2, x3, x4 <= 2;
> SOS2: x2, x3, x4, x5 <= 3;
>
> Thanks
> Richi Arora
>
>
>
>
>
>
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