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There is an exponential function on the denominator of my objective function

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  • Maliheh Aramon
    Gurobi Staff Gurobi Staff

    Hi, 

    You can use auxiliary decision variables as below:

    • \(y_j = -(\sum_{i=1}^{I} x_{ij} + \sum_{k=1}^{K} x_{kj}), ~~ \forall j \)
    • \(z_j = e^{y_j}, ~~ \forall j\)
    • \(u_j = \frac{2}{1+z_j} \rightarrow u_j + u_j z_j = 2, ~~\forall j\)
    • \(v = \sum_{j=1}^{J} u_j - 1\)
    • \(w = \frac{\sum_{j=1}^{J} (\sum_{i=1}^{I} x_{ij} r_i + \sum_{k=1}^{K} x_{kj} r_i )}{B_c}\)
    • \(q = \frac{w}{v} \rightarrow w = qv\)

    The objective function can then be just \(\max q\) and the above relationships should be implemented as constraints. 

    Best regards,

    Maliheh

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