added solutions to 3.1 and 3.2

exercises/ex03/solutions/bilevel.mod

+reset;
+
+var x{1..2} >= 0;
+var y{1..2} >= 0;
+var l{1..4} >= 0; # multipliers
+
+minimize f: - x[1]^2 - 3*x[2] - 4*y[1] + y[2]^2;
+
+subject to
+	c1: x[1]^2 + 2*x[2] <= 4;
+	F1: 2*y[1] + 2*l[1] - 3*l[2] - l[3] = 0;
+	F2: - 5 - l[1] + 4*l[2] - l[4] = 0;
+	F3: x[1]^2 - 2*x[1] + x[2]^2 - 2*y[1] + y[2] + 3 >= 0;
+	F4: x[2] + 3*y[1] - 4*y[2] - 4 >= 0;
+	cmpl1: l[1] * (x[1]^2 - 2*x[1] + x[2]^2 - 2*y[1] + y[2] + 3) = 0;
+	cmpl2: l[2] * (x[2] + 3*y[1] - 4*y[2] - 4) = 0;
+	cmpl3: l[3] * y[1] = 0;
+	cmpl4: l[4] * y[2] = 0;
+
+option solver knitro;
+option knitro_options "ms_enable=1 ms_maxsolves=30 ms_maxbndrange=5 outlev=2";
+
+#option solver couenne;
+
+solve;
+
+display _varname, _var;

exercises/ex03/solutions/bilevel_mpec.mod

+reset;
+
+var x{1..2} >= 0;
+var y{1..2} >= 0;
+var l{1..2} >= 0; # multipliers
+
+minimize f: - x[1]^2 - 3*x[2] - 4*y[1] + y[2]^2;
+
+subject to
+	c1: x[1]^2 + 2*x[2] <= 4;
+	F1: 2*y[1] + 2*l[1] - 3*l[2] = 0;
+	F2: - 5 - l[1] + 4*l[2] = 0;
+	cmpl1: 0 <= x[1]^2 - 2*x[1] + x[2]^2 - 2*y[1] + y[2] + 3 complements l[1] >= 0;
+	cmpl2: 0 <= x[2] + 3*y[1] - 4*y[2] - 4 complements l[2] >= 0;
+
+option solver knitro;
+option knitro_options "ms_enable=1 ms_maxsolves=30 ms_maxbndrange=5 outlev=2";
+
+#option solver couenne;
+
+solve;
+
+display _varname, _var;

exercises/ex03/solutions/knp2.mod

+reset;
+
+param n := 2; # dimensions
+param N := 6; # number of shperes
+
+var x{i in 1..N, j in 1..n} >= -1, <= 1 := Uniform(-1,1);
+var alpha;
+
+maximize obj: alpha;
+s.t. con1{i in 1..N}: sum{j in 1..n} x[i,j]^2 = 1;
+s.t. con2{i in 1..N, j in 1..N: i<j}:
+#	sum{k in 1..n} (x[i,k]-x[j,k])^2 >= 1;
+	sum{k in 1..n} (x[i,k]-x[j,k])^2 >= alpha;
+
+option solver ipopt;
+
+solve;
+
+display {i in 1..N} sum{j in 1..n} x[i,j]^2;
+display {i in 1..N, j in 1..N} sum{k in 1..n} (x[i,k]-x[j,k])^2;
+display alpha;

exercises/ex03/solutions/knp3.mod

+reset;
+
+param n := 3; # dimensions
+param N := 12; # number of shperes
+
+var x{i in 1..N, j in 1..n} >= -1, <= 1 := Uniform(-1,1);
+var alpha;
+
+maximize obj: alpha;
+s.t. con1{i in 1..N}: sum{j in 1..n} x[i,j]^2 = 1;
+s.t. con2{i in 1..N, j in 1..N: i<j}:
+#	sum{k in 1..n} (x[i,k]-x[j,k])^2 >= 1;
+	sum{k in 1..n} (x[i,k]-x[j,k])^2 >= alpha;
+
+option solver ipopt;
+
+solve;
+
+display {i in 1..N} sum{j in 1..n} x[i,j]^2;
+display {i in 1..N, j in 1..N} sum{k in 1..n} (x[i,k]-x[j,k])^2;
+display alpha;

exercises/ex03/solutions/knp4.mod

+reset;
+
+param n := 4; # dimensions
+param N := 24; # number of shperes
+
+var x{i in 1..N, j in 1..n} >= -1, <= 1 := Uniform(-1,1);
+var alpha;
+
+maximize obj: alpha;
+s.t. con1{i in 1..N}: sum{j in 1..n} x[i,j]^2 = 1;
+s.t. con2{i in 1..N, j in 1..N: i<j}:
+#	sum{k in 1..n} (x[i,k]-x[j,k])^2 >= 1;
+	sum{k in 1..n} (x[i,k]-x[j,k])^2 >= alpha;
+
+#option solver ipopt;
+
+option solver knitro;
+#option knitro_options "ms_enable=1 ms_maxsolves=30";
+
+solve;
+
+display {i in 1..N} sum{j in 1..n} x[i,j]^2;
+display {i in 1..N, j in 1..N} sum{k in 1..n} (x[i,k]-x[j,k])^2;
+display alpha;