
// UCLID5 model for traffic light control at an intersection
module traffic_light_control {
  // Define the state machine for traffic light phases
  type phase_t = enum { R, G, Y };

  // Variables for Main road light phases
  var mG : boolean;
  var mY : boolean;
  var mR : boolean;

  // Variables for Secondary road light phases
  var sG : boolean;
  var sY : boolean;
  var sR : boolean;

  // Variable for vehicle detection on Secondary road
  var vehicle_detected : boolean;

  // State machine logic, timing constraints, and transitions
  // (Pseudocode, requires implementation)

  // Safety requirement: When one light is G or Y, the other must be R
  invariant safety_requirement: (mG || mY) -> sR && (sG || sY) -> mR;

  // Output logic to control the light signals
  // (Pseudocode, requires implementation)

  // Control and verification blocks
  // (Pseudocode, requires implementation)
}
