Re: [Help-glpk] More conditional variables fun

2009-10-14 Thread Michael Hennebry
On Wed, 14 Oct 2009, Alexander Schnell wrote: > i have found out a formulation for your problem but the linear formulation is > quite long: > > the nonlinear formulation is quite short: > c = d*b*(b-a)+ e*a*(a-b). > > So now you can substitute the term d*b*(b-a) by the variable x and the term >

Re: [Help-glpk] More conditional variables fun

2009-10-14 Thread Yaron Kretchmer
Alex,Michael,Andrew,Larry- Thanks a lot for all the help and the great discussion. I'll summarize the different approaches in a separate email for future reference. Regards Kretch. On Wed, Oct 14, 2009 at 1:45 AM, Alexander Schnell wrote: > Hi there, > > i have found out a formulation for yo

Re: [Help-glpk] More conditional variables fun

2009-10-14 Thread Alexander Schnell
Hi there, i have found out a formulation for your problem but the linear formulation is quite long: the nonlinear formulation is quite short: c = d*b*(b-a)+ e*a*(a-b). So now you can substitute the term d*b*(b-a) by the variable x and the term e*a*(a-b) by the variable y. b*(b-a) is the produ

Re: [Help-glpk] More conditional variables fun

2009-10-14 Thread Michael Hennebry
On Tue, 13 Oct 2009, Yaron Kretchmer wrote: > Michael, > I'm sorry, but I didn't understand your explanation below- This is due to my > limited LP/MIP understanding- sigh.. You might want to look up convex hull and facet. > But, looking at the examples on > http://www.aimms.com/aimms/download/ma

Re: [Help-glpk] More conditional variables fun

2009-10-13 Thread Andrew Makhorin
> Now I #39;d like to be able to model conditional non-binary > variables. Does anybody know how to formulate this in mathprog? > --Begin Description --- > *) a,b are binary > *) c,d,e is continuous. > *) I #39;d like c to be >     - 0 if a=b=0 >     - d if a=0,b=1 >     -

Re: [Help-glpk] More conditional variables fun

2009-10-13 Thread Andrew Makhorin
> Now I #39;d like to be able to model conditional non-binary > variables. Does anybody know how to formulate this in mathprog? > --Begin Description --- > *) a,b are binary > *) c,d,e is continuous. > *) I #39;d like c to be >     - 0 if a=b=0 >     - d if a=0,b=1 >     -

Re: [Help-glpk] More conditional variables fun

2009-10-13 Thread Michael Hennebry
On Mon, 12 Oct 2009, Yaron Kretchmer wrote: > Thanks Michael > Yes, the differences (and the variables themselves) are bounded. We can > denote the the upper/lower limit for each variable/difference by the > constants l(x) and u(x). First, I made a mistake: The sets have seven extreme points each

Re: [Help-glpk] More conditional variables fun

2009-10-13 Thread Yaron Kretchmer
Michael, I'm sorry, but I didn't understand your explanation below- This is due to my limited LP/MIP understanding- sigh.. But, looking at the examples on http://www.aimms.com/aimms/download/manuals/AIMMS3OM_IntegerProgrammingTricks.pdfand doing some math led me to the following formulation:

Re: [Help-glpk] More conditional variables fun

2009-10-12 Thread Yaron Kretchmer
Thanks Michael Yes, the differences (and the variables themselves) are bounded. We can denote the the upper/lower limit for each variable/difference by the constants l(x) and u(x). What would the formulation be in that case? Regards Yaron On Mon, Oct 12, 2009 at 7:39 PM, Michael Hennebry < henn

Re: [Help-glpk] More conditional variables fun

2009-10-12 Thread Michael Hennebry
This might bounce from the mailing list. NDSU has been mucking with my return address. On Mon, 12 Oct 2009, Yaron Kretchmer wrote: > Now I'd like to be able to model conditional non-binary variables. Does > anybody know how to formulate this in mathprog? > > --Begin Description --

Re: [Help-glpk] More conditional variables fun

2009-10-12 Thread Michael Hennebry
This might bounce from the list. NDSU is mucking with my return address. Kretchmer wrote: > Thanks Larry. What I was looking for is for a way of forcing the "C" > variable to equal values per the truth table. > > If "C" was binary I could achieve this by a series of inequalities without > big M, a

Re: [Help-glpk] More conditional variables fun

2009-10-12 Thread Yaron Kretchmer
arry - TX > *Sent:* Monday, October 12, 2009 3:42 PM > *To:* Yaron Kretchmer; help-glpk > *Subject:* RE: [Help-glpk] More conditional variables fun > > > > Try thinking in terms of a Big M or large variable method. For instance… > > > > continuous variable expressio

RE: [Help-glpk] More conditional variables fun

2009-10-12 Thread D'Agostino, Larry - TX
f D'Agostino, Larry - TX Sent: Monday, October 12, 2009 3:42 PM To: Yaron Kretchmer; help-glpk Subject: RE: [Help-glpk] More conditional variables fun Try thinking in terms of a Big M or large variable method. For instance... continuous variable expression < (some large number) (binary var

Re: [Help-glpk] More conditional variables fun

2009-10-12 Thread Yaron Kretchmer
k-bounces+larry.d'agostino > =gmacrescap....@gnu.org] *On Behalf Of *Yaron Kretchmer > *Sent:* Monday, October 12, 2009 3:24 PM > *To:* help-glpk > *Subject:* [Help-glpk] More conditional variables fun > > > > Hi There. > Using feedback I got from the mailing list,

RE: [Help-glpk] More conditional variables fun

2009-10-12 Thread D'Agostino, Larry - TX
27;agostino=gmacrescap@gnu.org [mailto:help-glpk-bounces+larry.d'agostino=gmacrescap@gnu.org] On Behalf Of Yaron Kretchmer Sent: Monday, October 12, 2009 3:24 PM To: help-glpk Subject: [Help-glpk] More conditional variables fun Hi There. Using feedback I got from the mailing lis

[Help-glpk] More conditional variables fun

2009-10-12 Thread Yaron Kretchmer
Hi There. Using feedback I got from the mailing list, I was able to formulate binary conditional variables. Now I'd like to be able to model conditional non-binary variables. Does anybody know how to formulate this in mathprog? --Begin Description --- *) a,b are binary *)