param N := 4;

var x{1..N};

minimize f:
sum {i in 1..2} (1 - exp(-10*x[i]*exp(-1*x[i+2])));

subject to cons1:
x[1] + x[2] - 1 = 0;

subject to cons2:
x[3] + x[4] - 1 = 0;

subject to cons3{i in 1..4}:
0 <= x[i] <= 1;

data;
var x:=
1	0
2	0
3	0
4	0;

solve;

display x;