Hello List, I wrote some emails in the past months, thanks for the suggestions. The fact is that I am translating a complex model from C to Mason, and the scheduling thing is the one that puzzled me the most. I think I have something more reliable now, which looks something like: static void main(String[] args) throws Exception { SimState state = new SimulationEnvironment(System.currentTimeMillis()); state.nameThread(); doLoop(SimulationEnvironment.class, args); System.exit(0); } and a start() method like: public void start() { super.start(); marketSpace.clear(); // two Bag capitalGoodFirms.clear(); consumptionGoodFirms.clear(); for (int i = 0; i < N1; i++) { CapitalGoodFirm p = new CapitalGoodFirm(); p.setId(i); marketSpace.setObjectLocation(p, new Int2D(random.nextInt(marketSpace.getWidth()), random.nextInt(marketSpace.getHeight()))); capitalGoodFirms.add(p); } for (int i = 0; i < N2; i++) { ConsumptionGoodFirm p = new ConsumptionGoodFirm(); p.setId(i); marketSpace.setObjectLocation(p, new Int2D(random.nextInt(marketSpace.getWidth()), random.nextInt(marketSpace.getHeight()))); consumptionGoodFirms.add(p); } // do some stuff just once Initialize.initialize((SimulationEnvironment) this); // what agents have to do at each step schedule.scheduleRepeating( new Steppable() { @Override public void step(SimState state) { // this follows a bit the C structure I had, where different procedures // were called and each of the procedure called both agents types CallProcedureOne((SimulationEnvironment) state); CallProcedureTwo((SimulationEnvironment) state); ... } }, 0, 1); } My model is working now, so thanks for all the suggestions so far. Still, I would like a run to stop after 10 steps, this is a parameter that the user can set in the UI, but I don't know how to pass it to the SimState... I understand that from command line I can specify the maximum steps and the number of jobs, like do this simulation 20 times and each of the runs stops after 10 steps. What I am missing now is: is it possible to stop from the UI the simulation after x steps? Thanks in advance for your help. Best, Simone -- ----------------------------------------------------------------- Simone Gabbriellini, PhD Post-doctoral Researcher ANR founded research project "DIFFCERAM" GEMASS, CNRS & Paris-Sorbonne. mobile: +39 340 39 75 626 email: [log in to unmask]