\$title Car Sequencing (CARSEQ,SEQ=407) \$onText A number of cars are to be produced; they are not identical, because different options are available as variants on the basic model. The assembly line has different stations which install the various options (air-conditioning, sun-roof, etc.). These stations have been designed to handle at most a certain percentage of the cars passing along the assembly line. Furthermore, the cars requiring a certain option must not be bunched together, otherwise the station will not be able to cope. Consequently, the cars must be arranged in a sequence so that the capacity of each station is never exceeded. For instance, if a particular station can only cope with at most half of the cars passing along the line, the sequence must be built so that at most 1 car in any 2 requires that option. The problem has been shown to be NP-hard (Gent 1999). This is the example given in Dincbas, et al. More instances can be downloaded from CSPLib (problem prob001). Dincbas et al., Dincbas, M., Simonis, H., and Van Hentenryck, P. Solving the car-sequencing problem in constraint logic programming. In 8th European Conference on Artificial Intelligence (ECAI 88) , Y. Kodratoff, Ed. Pitmann Publishing, London, Munich, Germany, 290-295, 1988 Keywords: mixed integer linear programming, mixed integer nonlinear programming, production planning, car manufacturing, line problem \$offText Set p 'position' o 'options' c 'classes'; Parameter maxc(o) 'maximum number of cars with that option in a block' bs(o) 'block size to which the maximum number maxc refers' classData(c,*) 'class data'; \$if not set instance \$set instance \$ifThen '%instance%'=='' Set p 'position' / pos1*pos10 / o 'options' / opt1*opt5 / c 'classes' / class1*class6 /; Parameter maxc(o) 'maximum number of cars with that option in a block' / (opt1,opt3,opt5) 1, (opt2,opt4) 2 / bs(o) 'block size to which the maximum number maxc refers' / opt1 2, (opt2,opt3) 3, (opt4,opt5) 5 /; Table classData(c,*) 'class data' numCars opt1 opt2 opt3 opt4 opt5 class1 1 1 0 1 1 0 class2 1 0 0 0 1 0 class3 2 0 1 0 0 1 class4 2 0 1 0 1 0 class5 2 1 0 1 0 0 class6 2 1 1 0 0 0; \$else \$onEcho > cs.awk BEGIN { nr=1 } !/^#/ { if (nr==1) { o = \$2; printf("set p /1*%d/, o /1*%d/, c /1*%d/\n", \$1,o,\$3) } if (nr==2) { printf("Parameter maxc(o) / 1 %d", \$1); for (j=2; j<=o; j++) printf(", %d %d", j, \$j); printf("/\n"); } if (nr==3) { printf("Parameter bs(o) / 1 %d", \$1); for (j=2; j<=o; j++) printf(", %d %d", j, \$j); printf("/\n"); } if (nr==4) { printf("Table classData(c,*)\n\$ondelim\nclass,numCars"); for (j=1; j<=o; j++) printf(",%d", j); printf("\n"); } if (nr>3) { printf("%d,%d", \$1+1, \$2) for (j=1; j<=o; j++) printf(",%d", \$(j+2)); printf("\n"); } nr++; } END { printf("\$offdelim\n;") } \$offEcho \$call awk -f cs.awk %instance% > "%gams.scrdir%csinst.%gams.scrext%" \$ifE errorLevel<>0 \$abort Problems running awk \$include "%gams.scrdir%csinst.%gams.scrext%" \$endIf abort\$(card(p) <> sum(c, classData(c,'numCars'))) 'inconsistent number of cars'; Alias (p,pp); Set blk(o,p) 'blocks of positions to monitor' blkc(o,p,pp) 'positions in the blocks'; blkc(o,p,pp)\$(ord(p) <= card(p) - bs(o) + 1) = ord(pp) >= ord(p) and ord(pp) < ord(p) + bs(o); blk(o,p) = sum(pp\$blkc(o,p,pp), 1); Variable sumc(o,p) cp(c,p) 'class k is scheduled at position p' op(o,p) 'option o appears at position p' v(o,p) 'violations in a block' obj 'sum of violations'; Binary Variable cp; \$ifThen set MIP Positive Variable v; Binary Variable op; \$endIf Equation defnumCars(c) 'exactly numCars of class c assigned to positions' defoneCar(p) 'one car assigned to each position p' defop(o,p) 'option o appears at position p' defopLS(o,p) 'option o appears at position p' defviol(o,p) 'violations in a block' defviolLS(o,p) 'violations in a block' defobj 'minimize violations' defsumc(o,p); defnumCars(c).. sum(p, cp(c,p)) =e= classData(c,'numCars'); defoneCar(p).. sum(c, cp(c,p)) =e= 1; defop(o,p).. sum(c\$classData(c,o),cp(c,p)) =l= op(o,p); defsumc(o,p).. sumc(o,p) =e= sum(c\$classData(c,o),cp(c,p)); defopLS(o,p).. op(o,p) =e= ifthen(sumc(o,p) >= 0.5, 1, 0); * defopLS(o,p).. op(o,p) =e= ifthen(sum(c\$classData(c,o),cp(c,p)) > 0.5, 1, 0); defviol(blk(o,p)).. sum(blkc(blk,pp), op(o,pp)) =l= maxc(o) + v(o,p); defviolLS(blk(o,p)).. v(o,p) =e= max(sum(blkc(blk,pp), op(o,pp)) - maxc(o), 0); defobj.. obj =e= sum(blk(o,p), v(o,p)); Model carseqMIP / all - defopLS - defviolLS - defsumc / carseqLS / all - defop - defviol /; option optCr = 0; \$ifThen set MIP Positive Variable v; Binary Variable op; solve carseqMIP min obj using mip; \$else solve carseqLS min obj using minlp; \$endIf Parameter rep(p,c,o); rep(p,c,o)\$(cp.l(c,p) > 0.5) = classData(c,o); option rep:0:2:1; display rep;