Initializing help system before first use

Burglar - introductory MIP model


Type: Knapsack problem
Rating: 1 (simple)
Description: Modeling and solving a small MIP problem (burglar.mos), alternative version demonstrating the use of index sets of type string (burglari.mos)
File(s): burglar.mos, burglari.mos


burglar.mos
(!******************************************************
   Mosel User Guide Example Problems
   ================================= 

   file burglar.mos
   ````````````````
   Small MIP problem.
   
   (c) 2008 Fair Isaac Corporation
       author: S. Heipcke, 2001
*******************************************************!)

model Burglar 
 uses "mmxprs"
  
 declarations
  WTMAX = 102                    ! Maximum weight allowed
  ITEMS = 1..8                   ! Index range for items
  
  VALUE: array(ITEMS) of real    ! Value of items
  WEIGHT: array(ITEMS) of real   ! Weight of items
  
  take: array(ITEMS) of mpvar    ! 1 if we take item i; 0 otherwise
 end-declarations

! Item:      1   2   3   4   5   6   7   8
  VALUE :: [15, 100, 90, 60, 40, 15, 10,  1]
  WEIGHT:: [ 2,  20, 20, 30, 40, 30, 60, 10]

! Objective: maximize total value
 MaxVal:= sum(i in ITEMS) VALUE(i)*take(i) 

! Weight restriction
 sum(i in ITEMS) WEIGHT(i)*take(i) <= WTMAX

! All variables are 0/1
 forall(i in ITEMS) take(i) is_binary  

 maximize(MaxVal)                 ! Solve the MIP-problem

! Print out the solution
 writeln("Solution:\n Objective: ", getobjval)
 forall(i in ITEMS)  writeln(" take(", i, "): ", getsol(take(i)))
end-model

burglari.mos
(!******************************************************
   Mosel User Guide Example Problems
   ================================= 

   file burglari.mos
   `````````````````
   Use of index sets.
   
   (c) 2008 Fair Isaac Corporation
       author: S. Heipcke, 2001, rev. 2006
*******************************************************!)

model "Burglar (index set)"
 uses "mmxprs"
 
 declarations
  WTMAX = 102                    ! Maximum weight allowed
  ITEMS = {"camera", "necklace", "vase", "picture", "tv", "video", 
           "chest", "brick"}     ! Index set for items
  
  VALUE: array(ITEMS) of real    ! Value of items
  WEIGHT: array(ITEMS) of real   ! Weight of items
  
  take: array(ITEMS) of mpvar    ! 1 if we take item i; 0 otherwise
 end-declarations

 VALUE("camera")  := 15;  WEIGHT("camera")  :=  2
 VALUE("necklace"):=100;  WEIGHT("necklace"):= 20
 VALUE("vase")    := 90;  WEIGHT("vase")    := 20
 VALUE("picture") := 60;  WEIGHT("picture") := 30
 VALUE("tv")      := 40;  WEIGHT("tv")      := 40
 VALUE("video")   := 15;  WEIGHT("video")   := 30
 VALUE("chest")   := 10;  WEIGHT("chest")   := 60
 VALUE("brick")   :=  1;  WEIGHT("brick")   := 10

(! Alternative initialization of data arrays:
 VALUE :: (["camera", "necklace", "vase", "picture", "tv", "video", 
            "chest", "brick"])[15,100,90,60,40,15,10,1]
 WEIGHT:: (["camera", "necklace", "vase", "picture", "tv", "video", 
            "chest", "brick"])[2,20,20,30,40,30,60,10]
!)

! Objective: maximize total value
 MaxVal:= sum(i in ITEMS) VALUE(i)*take(i) 

! Weight restriction
 sum(i in ITEMS) WEIGHT(i)*take(i) <= WTMAX

! All variables are 0/1
 forall(i in ITEMS) take(i) is_binary  

 maximize(MaxVal)                 ! Solve the MIP-problem

! Print out the solution
 writeln("Solution:\n Objective: ", getobjval)
 forall(i in ITEMS)  writeln(" take(", i, "): ", getsol(take(i)))
end-model