Elimination constraint & subset usage

Hello guys,

I’m working on a vehicle routing problem. I was able to code the model somehow and got a result. But the results are undesirable sub-tours. I want to add sub-tour elimination constraints. An example is available below:
image.png
I have 15 stops and that means I add this constraint for 2**15 subsets. How can I generate sets of subtours and process this equation for each sub-set. Can you help me?

Either use the compact Miller, Tucker and Zemlin formulation to avoid subtours or build up only the necessary subtour elimination constraints. Both are done here: https://www.gams.com/latest/gamslib_ml/libhtml/gamslib_tsp5.html

-Michael