摘要：A theoretical model is developed for the ratio primary-surplus/GDP that a Country has to attain over a given number of years, to lower its public debt from the present value to one a-priori fixed. Such a ratio depends on the average interest rate paid on the outstanding stock of debt as well as inflation and real growth rates. The ratio primary-surplus/GDP is then determined for Germany, Greece and Italy, supposing that 20 years are necessary for lowering the debt to 60% of GDP, as indicated in the Budget Pact approved by 25 EU member States. Results are reported in graphs and show how the German debt can be easily diminished, whilst debts in Greece and Italy can be reduced with a greater difficulty.
关键词：public debt, primary surplus, Italian economy, greek economy
