At least n variables not zero

[annaf02]

Dear All,

Is it possible to ask lpsolve to find a solution of a problem with say m variables such that at least n (<m) of them are not zero?
I had a look at the special ordered sets but it seems to be something like the opposite of the restriction I am looking for.

Any help is very much appreciated.
Anna

[Peter Notebaert-2]

You will have to use binary variables for that.

For each variable in your model you will have to add an extra binary variable, add constraints to make it 0 if your variable is 0 and 1 if non-zero and then add an extra contraint that the sum of the added binary vars is >= n

Peter

--- In lp_solve@..., "annaf02" <annaf02@...> wrote:
>
> Dear All,
>
> Is it possible to ask lpsolve to find a solution of a problem with say m variables such that at least n (<m) of them are not zero?
> I had a look at the special ordered sets but it seems to be something like the opposite of the restriction I am looking for.
>
> Any help is very much appreciated.
> Anna
>

[annaf02]

Peter,

Thank you ever so much!

Anna

--- In lp_solve@..., "peter_notebaert" <_peno_@...> wrote:

>
> You will have to use binary variables for that.
>
> For each variable in your model you will have to add an extra binary variable, add constraints to make it 0 if your variable is 0 and 1 if non-zero and then add an extra contraint that the sum of the added binary vars is >= n
>
> Peter
>
> --- In lp_solve@..., "annaf02" <annaf02@> wrote:
> >
> > Dear All,
> >
> > Is it possible to ask lpsolve to find a solution of a problem with say m variables such that at least n (<m) of them are not zero?
> > I had a look at the special ordered sets but it seems to be something like the opposite of the restriction I am looking for.
> >
> > Any help is very much appreciated.
> > Anna
> >
>