Location problem — linear programming












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$begingroup$


I have a location problem I need help with:



Suppose a boat company wants to operate services between 11 ports in a city. The number of return journeys between port i and port j is denoted by a x-variable (Xij), i and j = 1 to 11. Now I need to impose a constraint such that the number of return journeys between the same pair of ports does not exceed 3. That is, e.g. there can be at most 3 return journeys made between port 1 and port 2.



I know I can do it by Xij + Xji <= 3, but this would result in tons of constraints...



Can anyone come up with a compact form of this constraint? Thank you in advance!










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  • $begingroup$
    an alternative is Benders' decomposition, but I'd rather add those 55 constraints
    $endgroup$
    – LinAlg
    Dec 18 '18 at 17:55










  • $begingroup$
    Think I'd rather do the same as well and keep it simple, thanks!
    $endgroup$
    – HFCH
    Dec 18 '18 at 18:08










  • $begingroup$
    It is just one line: $large{x_{ij}+x_{ji}leq 3 forall i,jin {1,2, ldots , 11}}$
    $endgroup$
    – callculus
    Dec 18 '18 at 18:43










  • $begingroup$
    @callculus, this is what I have arrived at too. Thanks for confirming!
    $endgroup$
    – HFCH
    Dec 18 '18 at 19:23
















0












$begingroup$


I have a location problem I need help with:



Suppose a boat company wants to operate services between 11 ports in a city. The number of return journeys between port i and port j is denoted by a x-variable (Xij), i and j = 1 to 11. Now I need to impose a constraint such that the number of return journeys between the same pair of ports does not exceed 3. That is, e.g. there can be at most 3 return journeys made between port 1 and port 2.



I know I can do it by Xij + Xji <= 3, but this would result in tons of constraints...



Can anyone come up with a compact form of this constraint? Thank you in advance!










share|cite|improve this question









$endgroup$












  • $begingroup$
    an alternative is Benders' decomposition, but I'd rather add those 55 constraints
    $endgroup$
    – LinAlg
    Dec 18 '18 at 17:55










  • $begingroup$
    Think I'd rather do the same as well and keep it simple, thanks!
    $endgroup$
    – HFCH
    Dec 18 '18 at 18:08










  • $begingroup$
    It is just one line: $large{x_{ij}+x_{ji}leq 3 forall i,jin {1,2, ldots , 11}}$
    $endgroup$
    – callculus
    Dec 18 '18 at 18:43










  • $begingroup$
    @callculus, this is what I have arrived at too. Thanks for confirming!
    $endgroup$
    – HFCH
    Dec 18 '18 at 19:23














0












0








0





$begingroup$


I have a location problem I need help with:



Suppose a boat company wants to operate services between 11 ports in a city. The number of return journeys between port i and port j is denoted by a x-variable (Xij), i and j = 1 to 11. Now I need to impose a constraint such that the number of return journeys between the same pair of ports does not exceed 3. That is, e.g. there can be at most 3 return journeys made between port 1 and port 2.



I know I can do it by Xij + Xji <= 3, but this would result in tons of constraints...



Can anyone come up with a compact form of this constraint? Thank you in advance!










share|cite|improve this question









$endgroup$




I have a location problem I need help with:



Suppose a boat company wants to operate services between 11 ports in a city. The number of return journeys between port i and port j is denoted by a x-variable (Xij), i and j = 1 to 11. Now I need to impose a constraint such that the number of return journeys between the same pair of ports does not exceed 3. That is, e.g. there can be at most 3 return journeys made between port 1 and port 2.



I know I can do it by Xij + Xji <= 3, but this would result in tons of constraints...



Can anyone come up with a compact form of this constraint? Thank you in advance!







linear-programming integer-programming






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share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Dec 18 '18 at 11:47









HFCHHFCH

83




83












  • $begingroup$
    an alternative is Benders' decomposition, but I'd rather add those 55 constraints
    $endgroup$
    – LinAlg
    Dec 18 '18 at 17:55










  • $begingroup$
    Think I'd rather do the same as well and keep it simple, thanks!
    $endgroup$
    – HFCH
    Dec 18 '18 at 18:08










  • $begingroup$
    It is just one line: $large{x_{ij}+x_{ji}leq 3 forall i,jin {1,2, ldots , 11}}$
    $endgroup$
    – callculus
    Dec 18 '18 at 18:43










  • $begingroup$
    @callculus, this is what I have arrived at too. Thanks for confirming!
    $endgroup$
    – HFCH
    Dec 18 '18 at 19:23


















  • $begingroup$
    an alternative is Benders' decomposition, but I'd rather add those 55 constraints
    $endgroup$
    – LinAlg
    Dec 18 '18 at 17:55










  • $begingroup$
    Think I'd rather do the same as well and keep it simple, thanks!
    $endgroup$
    – HFCH
    Dec 18 '18 at 18:08










  • $begingroup$
    It is just one line: $large{x_{ij}+x_{ji}leq 3 forall i,jin {1,2, ldots , 11}}$
    $endgroup$
    – callculus
    Dec 18 '18 at 18:43










  • $begingroup$
    @callculus, this is what I have arrived at too. Thanks for confirming!
    $endgroup$
    – HFCH
    Dec 18 '18 at 19:23
















$begingroup$
an alternative is Benders' decomposition, but I'd rather add those 55 constraints
$endgroup$
– LinAlg
Dec 18 '18 at 17:55




$begingroup$
an alternative is Benders' decomposition, but I'd rather add those 55 constraints
$endgroup$
– LinAlg
Dec 18 '18 at 17:55












$begingroup$
Think I'd rather do the same as well and keep it simple, thanks!
$endgroup$
– HFCH
Dec 18 '18 at 18:08




$begingroup$
Think I'd rather do the same as well and keep it simple, thanks!
$endgroup$
– HFCH
Dec 18 '18 at 18:08












$begingroup$
It is just one line: $large{x_{ij}+x_{ji}leq 3 forall i,jin {1,2, ldots , 11}}$
$endgroup$
– callculus
Dec 18 '18 at 18:43




$begingroup$
It is just one line: $large{x_{ij}+x_{ji}leq 3 forall i,jin {1,2, ldots , 11}}$
$endgroup$
– callculus
Dec 18 '18 at 18:43












$begingroup$
@callculus, this is what I have arrived at too. Thanks for confirming!
$endgroup$
– HFCH
Dec 18 '18 at 19:23




$begingroup$
@callculus, this is what I have arrived at too. Thanks for confirming!
$endgroup$
– HFCH
Dec 18 '18 at 19:23










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