> Put a sticker on it marked "clean". The sticker/magnet doesn't work. What works is maintaining the invariant "if the door is locked, the dishes inside are c

> Put a sticker on it marked "clean". The sticker/magnet doesn't work. What works is maintaining the invariant "if the door is locked, the dishes inside are clean". If you open a locked door, you either empty the dishwasher or relock the door.