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From: | Yaron Kretchmer |
Subject: | Re: [Help-glpk] More conditional variables fun |
Date: | Mon, 12 Oct 2009 20:32:08 -0700 |
This might bounce from the list.
NDSU is mucking with my return address.In my previous post, I seem to have misinterpreted the question.
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, and I'm just wondering what would be the formulation for non-binary
variables.
Unless you have bounds on the differences in the variables,
there isn't any good way.
With bounds on the differences,
the feasible sets of (a,b,c-d) and (a,b,c-e)
have four extreme points.
Their convex hulls are tetrahedra.
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
*) c,d,e is continuous.
*) I'd like c to be
- 0 if a=b=0
- d if a=0,b=1
- e if a=1,b=0
- 0 if a=b=1
----------End Description
--
Michael address@hidden
"Pessimist: The glass is half empty.
Optimist: The glass is half full.
Engineer: The glass is twice as big as it needs to be."
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