1.1 Problem restatement and analysis
The earth resources are finite while the humans consumption is increasing.For long-term development,we need a sustainable development model.In the paper,we need to build a mathematical model to measure the sustainable development of a country,and select a country to develop its 20-year plan for sustainable development and take into account a variety of factors to predict the development of the country after 20 years.
To accomplish these,we need to solve the following problems：
•Define the boundary between sustainable development and unsustainable development.
•Make predictions on the 20-year development of the country under existing conditions.
•Develop a sustainable development plan against major factors which have effect on the sustainable development of the country.
•Consider more factors to predict the development of the country after 20 years with the implementation of the new plan.