! Keywords: Airlines / Communications / Distribution / Geographic / !Network / !Petroleum Industry / Scheduling / Shipping / Shortest Route ! / Transportation;
! LINDO format Fleet routing with a single plane type; 
! We want to schedule planes to cover the following
! schedule of 11 flights that repeats every day. 
!  See the text Optimization Modeling with LINGO for more details.
!            City           Time
! Flight Depart Arrive Depart Arrive
!  1 221  ORD    DEN    0800   0934
!  2 223  ORD    DEN    0900   1039
!  3 274  LAX    DEN    0800   1116
!  4 105  ORD    LAX    1100   1314
!  5 228  DEN    ORD    1100   1423
!  6 230  DEN    ORD    1200   1521
!  7 259  ORD    LAX    1400   1609
!  8 293  DEN    LAX    1400   1510
!  9 412  LAX    ORD    1400   1959
! 10 766  LAX    DEN    1600   1912
! 11 238  DEN    ORD    1800   2121
!
!  Minimize number of planes on ground overnight;
MIN  GC2400 + GD2400 + GL2400
 ST
! The plane (old) conservation constraints;
! Chicago at 8 am,  sources - uses = 0;
 + GC2400 - F221 - F223 - F105 - F259 - GC1400 = 0
! Chicago at midnight;
 GC1400 + F228 + F230 + F412+ F238 - GC2400 = 0
! Denver at 11 am;
 GD2400 + F221 + F223 - F228 - GD1100 = 0
! Denver at high noon;
 GD1100 + F274 - F230 - F293 - F238 - GD1800 = 0
! Denver at midnight;
 GD1800 + F766 - GD2400 = 0
! LA at 8 am;
 GL2400 - F274 - GL0800 = 0
! LA  at 1400;
 GL0800 + F105 - F412 - GL1400 = 0
! LA  at 1600;
 GL1400 + F293 - F766 - GL1600 = 0
! LA  at midnight;
 GL1600 + F259 - GL2400 = 0
! Cover our flights constraints;
 F221 = 1
 F223 = 1
 F274 = 1
 F105 = 1
 F228 = 1
 F230 = 1
 F259 = 1
 F293 = 1
 F412 = 1
 F766 = 1
 F238 = 1
END