profit optimization In the early 20th century, famous American economist elvin fisher developed the theory of economic gain. In its book "the nature of capital and yield", first, the concept of yield is analyzed in terms of the performance of earnings, and three different types of benefits are proposed: The deregistration of shares refers to the reduction of a part of the company's shares in accordance with the issuing procedure. The total write-off of the company's shares only occurs when the company is dissolved. In addition, through the buyback of shares and the merger of the company with the shares of the company, it can also achieve the purpose of the cancellation of shares Interest rate, in the form of expression, refers to the ratio of the amount of interest to the total amount of borrowed capital in a certain period of time.  the interest rate is the interest level per unit time of the unit currency, indicating the interest rate. Economists have been looking for a theory that can fully explain the structure and change of interest rates. Interest rates are usually controlled by the central bank of the country and administered by the federal reserve board in the United States. Today, interest rates are one of the important tools for macroeconomic regulation. But to increase political accountability and to sacrifice the independence of the central bank is to throw the baby out of the bath. Monetary policy is complex and technical. Handing control to politicians is more prudent than handing over keys to the country's nuclear power plants. As hicks income concept did not specify what is called "equal wealth", and thus the income concept formed the basis of many debates concept, and the theory of accounting earnings, especially the capital preservation theory has a great influence. In accounting, people used to call "maintaining the same level of affluence" as capital preservation.