The plus and minus signs in systems notation must be read as conditional propositions. So – in this post’s picture of systems notation in a small concept map – if the furnace operation is increased, the temperature will go up. And if the temperature increases, the temperature gap with the thermostat setting will decrease, hence the minus sign. If the thermostat is set higher, the temperature gap will widen. If the temperature gap increases, the furnace operation will be enhanced. The introduction of systems notation in concept mapping seems to make sense. It is hard to see how this type of propositions can be used in concept mapping without this special form of notation. A question remains as to how the combination of two types of propositions will work out in a single map.