The model's workings can be described in terms of an IS-LM-BoP graph with the domestic interest rate plotted vertically and real GDP plotted horizontally. The IS curve is downward sloped and the LM curve is upward sloped, as in the closed economy IS-LM analysis; the BoP curve is upward sloped unless there is perfect capital mobility, in which case it is horizontal at the level of the world interest rate. In this graph, under less than perfect capital mobility the positions of both the IS curve and the BoP curve depend on the exchange rate (as discussed below), since the IS-LM graph is actually a two-dimensional cross-section of a three-dimensional space involving all of the interest rate, income, and the exchange rate. However, under perfect capital mobility the BoP curve is simply horizontal at a level of the domestic interest rate equal to the level of the world interest rate. Summary of potency of monetary and fiscal policy As explained below, whether domestic monetary or fiscal policy is potent, in the sense of having an effect on real GDP, depends on the exchange rate regime. The results are summarized here. Flexible exchange rates: Domestic monetary policy affects GDP, while fiscal policy does not. Fixed exchange rates: Fiscal policy affects GDP, while domestic monetary policy does not. Flexible exchange rate regime In a system of flexible exchange rates, central banks allow the exchange rate to be determined by market forces alone. Changes in the money supply An increase in money supply shifts the LM curve to the right. This directly reduces the local interest rate relative to the global interest rate. That being said, capital outflows will increase which will lead to a decrease in the real exchange rate, ultimately shifting the IS curve right until interest rates equal global interest rates (assuming horizontal BOP). A decrease in the money supply causes the exact opposite process. Changes in government spending An increase in government expenditure shifts the IS curve to the right. This will mean that domestic interest rates and GDP rise. However, this increase in the interest rates attracts foreign investors wishing to take advantage of the higher rates, so they demand the domestic currency, and therefore it appreciates. The strengthening of the currency will mean it is more expensive for customers of domestic producers to buy the home country's exports, so net exports will decrease, thereby cancelling out the