diff -r d59bea55db9b -r c445c931472f examples/gap.mod
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+++ b/examples/gap.mod	Mon Dec 06 13:09:21 2010 +0100
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+/* GAP, Generalized Assignment Problem */
+
+/* Written in GNU MathProg by Andrew Makhorin <mao@gnu.org> */
+
+/* The Generalized Assignment Problem (GAP) is to assign a set of jobs
+   to a set of agents subject to the constraints that each job must be
+   assigned exactly to one agent and the total resources consumed by all
+   jobs assigned to an agent must not exceed the agent's capacity. */
+
+param m, integer, > 0;
+/* number of agents */
+
+param n, integer, > 0;
+/* number of jobs */
+
+set I := 1..m;
+/* set of agents */
+
+set J := 1..n;
+/* set of jobs */
+
+param a{i in I, j in J}, >= 0;
+/* resource consumed in allocating job j to agent i */
+
+param b{i in I}, >= 0;
+/* resource capacity of agent i */
+
+param c{i in I, j in J}, >= 0;
+/* cost of allocating job j to agent i */
+
+var x{i in I, j in J}, binary;
+/* x[i,j] = 1 means job j is assigned to agent i */
+
+s.t. one{j in J}: sum{i in I} x[i,j] = 1;
+/* job j must be assigned exactly to one agent */
+
+s.t. lim{i in I}: sum{j in J} a[i,j] * x[i,j] <= b[i];
+/* total amount of resources consumed by all jobs assigned to agent i
+   must not exceed the agent's capacity */
+
+minimize obj: sum{i in I, j in J} c[i,j] * x[i,j];
+/* the objective is to find cheapest assignment (note that gap can also
+   be formulated as maximization problem) */
+
+data;
+
+/* These data correspond to the instance c515-1 (gap1) from:
+
+   I.H. Osman, "Heuristics for the Generalised Assignment Problem:
+   Simulated Annealing and Tabu Search Approaches", OR Spektrum, Volume
+   17, 211-225, 1995
+
+   D. Cattrysse, M. Salomon and L.N. Van Wassenhove, "A set partitioning
+   heuristic for the generalized assignment problem", European Journal
+   of Operational Research, Volume 72, 167-174, 1994 */
+
+/* The optimal solution is 261 (minimization) or 336 (maximization) */
+
+param m := 5;
+
+param n := 15;
+
+param a :  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 :=
+      1    8 15 14 23  8 16  8 25  9 17 25 15 10  8 24
+      2   15  7 23 22 11 11 12 10 17 16  7 16 10 18 22
+      3   21 20  6 22 24 10 24  9 21 14 11 14 11 19 16
+      4   20 11  8 14  9  5  6 19 19  7  6  6 13  9 18
+      5    8 13 13 13 10 20 25 16 16 17 10 10  5 12 23 ;
+
+param b := 1 36, 2 34, 3 38, 4 27, 5 33;
+
+param c :  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 :=
+      1   17 21 22 18 24 15 20 18 19 18 16 22 24 24 16
+      2   23 16 21 16 17 16 19 25 18 21 17 15 25 17 24
+      3   16 20 16 25 24 16 17 19 19 18 20 16 17 21 24
+      4   19 19 22 22 20 16 19 17 21 19 25 23 25 25 25
+      5   18 19 15 15 21 25 16 16 23 15 22 17 19 22 24 ;
+
+end;