Originally posted by: Bo7

Hello,
I will explain my problem with an example
Let's say that i have these constraints :
d2 - d1 <= 7
d2 - d1 >= 5
d3 - d2 <= 100
d3 - d2 >= 1
d3 - d1 <= 107
d3 - d1 >= 6

I want to maximize the difference between each pair of nodes what i do now is changing my objective function each time and then solve the problem (example: max d1-d2 then d1-d3 then d2-d3....) but i don't think it is the right solution so i hope that there is someone who can help me to better formulate my objective function to have all the diffrences between each pair of nodes calculated in one time.

Thank you in advance
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

Simultaneously maximizing all pairwise differences is not possible (other than by cosmic coincidence). Do you want to maximize the sum of the differences? If so, just add them up in the objective function (weighted if you so choose).

/Paul
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: Bo7

Thank you for your answer no i just need the max diffrence between each two nodes. my problem is like shortest (longest) path problem. but i need to maximize the distance between each pair of nodes and have this value to fill a matrice ( like ford warshall algorithm).
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

Not sure if I got you correctly. You want to maximize the maximal distance? Like this:

max maxdist

maxdist <= d2 - d1
maxdist <= d3 - d1
maxdist <= d2 - d2

In this model 'maxdist' would be as big as possible.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: Bo7

no i'm looking for the maximum dufference (distance between each pair of nodes and then put the results in a matrice which represent the maximum diffrence between each two nodes. Actually i change everytime the objective function to get these results.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

Your approach is how I would do it.

/Paul
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: future987

To sketch the region represented by a linear inequality in two variables:

A. Sketch the straight line obtained by replacing the inequality with an equality.

B. Choose a test point not on the line ((0,0) is a good choice if the line does not pass through the origin, and if the line does pass through the origin a point on one of the axes would be a good choice).

C. If the test point satisfies the inequality, then the set of solutions is the entire region on the same side of the line as the test point. Otherwise it is the region on the other side of the line. In either case, shade out the side that does not contain the solutions, leaving the solution region showing.
[url=http://www.2funbd.com]BD[/url]
[url=http://www.2funbd.com/forum]BD Forum[/url]
[url=http://www.2funbd.com/Blog]BD Blog[/url
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: Bo7

Thank you
#CPLEXOptimizers
#DecisionOptimization