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Ground transport Description
Further explanation of this example:
'Applications of optimization with Xpress-MP', Chapter 10: Ground transport
Source Files
Data Files
e4deliver.mos (!****************************************************** Mosel Example Problems ====================== file e4deliver.mos `````````````````` Heating oil delivery (Traveling Salesman Problem) (c) 2008 Fair Isaac Corporation author: S. Heipcke, Mar. 2002 *******************************************************!) model "E-4 Oil delivery" uses "mmxprs" declarations NS = 7 SITES = 1..NS ! Set of locations, 1=refinery CLIENTS = 2..NS DEM: array(SITES) of integer ! Demands DIST: array(SITES,SITES) of integer ! Distances between locations CAP: integer ! Lorry capacity prec: array(SITES,SITES) of mpvar ! 1 if i immediately precedes j, ! 0 otherwise quant: array(CLIENTS) of mpvar ! Quantity delivered up to i end-declarations initializations from 'e4deliver.dat' DEM DIST CAP end-initializations ! Objective: total distance driven Length:= sum(i,j in SITES | i<>j) DIST(i,j)*prec(i,j) ! Enter and leave every city only once (except the depot) forall(j in CLIENTS) sum(i in SITES| i<>j) prec(i,j) = 1 forall(i in CLIENTS) sum(j in SITES| i<>j) prec(i,j) = 1 ! If i is the first client of a tour, then quant(i)=DEM(i) forall(i in CLIENTS) quant(i) <= CAP + (DEM(i)-CAP)*prec(1,i) ! If j comes just after i in a tour, then quant(j) is greater than the ! quantity delivered during the tour up to i plus the quantity to be ! delivered at j (to avoid loops and keep capacity limit of the tanker) forall(i,j in CLIENTS| i<>j) quant(j) >= quant(i) + DEM(j) - CAP + CAP*prec(i,j) + (CAP-DEM(j)-DEM(i))*prec(j,i) ! Additional constraints: ! If i is not the first client of a tour, quant(i) is larger than the sum ! of the quantities to deliver to i and to his predecessor on the tour (! declarations modcut: array(CLIENTS) of linctr end-declarations forall(i in CLIENTS) do modcut(i):= quant(i) >= DEM(i) + sum(j in SITES| i<>j) DEM(j)*prec(j,i) setmodcut(modcut(i)) end-do !) forall(i in CLIENTS) do quant(i) <= CAP quant(i) >= DEM(i) end-do forall(i,j in SITES | i<>j) prec(i,j) is_binary ! Uncomment the following line to see the Optimizer log ! setparam("XPRS_VERBOSE",true) ! Solve the problem minimize(Length) ! Solution printing writeln("Total distance: ", getobjval) forall(i in CLIENTS) if(getsol(prec(1,i))>0) then ct:=DEM(i) writeln(1, " -> ", i) p:=i while(p<>1) do n:= integer(round(sum(j in SITES) j*getsol(prec(p,j)))) writeln(p, " -> ", n) ct+=DEM(n) p:=n end-do writeln("Quantity delivered: ", ct) end-if end-model | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

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