gams:model_permutations

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gams:model_permutations [2007/08/10 11:04] 127.0.0.1 external edit |
gams:model_permutations [2020/05/20 12:02] (current) Frederik Fiand |
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====== Modeling permutations ====== | ====== Modeling permutations ====== | ||

+ | Q: //How can I model a vector of integer variables x(i) that can assume values 1,2,...,card(i), and each x(i) should be different, i.e. ''x(i) <> x(j) for all i <> j'' ?// | ||

- | How can I model in GAMS the following restriction? A vector of integer variables x(i) can assume values 1,2,...,card(i), and each x(i) should be different, i.e. | + | This looks like we need the help of a permutation matrix ''P=p(i,j)'', |

- | | + | |

- | x(i) <> x(j) for all i <> j | + | |

- | | + | |

- | This looks like we need the help of a permutation matrix P=pij, | + | |

where there is exactly one 1 in each row and column, and the other | where there is exactly one 1 in each row and column, and the other | ||

elements are zero. The identity matrix is a trivial example of a | elements are zero. The identity matrix is a trivial example of a |

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gams/model_permutations.txt · Last modified: 2020/05/20 12:02 by Frederik Fiand