Hello, I need to create a permission with a complex set of unions and intersections. Something like:

definition sample/registration {
  relation learner: sample/student;
  relation target: sample/formation;

  permission subscribe = (target->subscribe & learner->subscribe) + learner->self
}

Is it possible to use parenthesis to priorize the operations ? Otherwise, how can we do this kind of things in rebac ? Thanks (sorry for the noob question !)