How to define a binary variable in non linear constraints

if x(1)+x(2)+x(3)> 0 then x(4)= 1 otherwise x(4)=0

[John D'Errico]

Please stop asking the same question multiple times.

Answer 1

[Torsten]

Solve two problems:

One with

x(1)+x(2)+x(3)>= 0
x(4)=1

the other with

x(1)+x(2)+x(3)<= 0
x(4)=0

and take the best of the two runs as the solution.