Democrats in the US say that taxes can be used to "grease the wheels" of the economy and create wealth enough to recover taxes and thereby increase employment; the Republicans say that taxation discourages investment and so increases unemployment. These arguments cannot both be correct, but both...

The duality principle in option pricing aims at simplifying valuation problems that depend on several variables by associating them to the corresponding dual option pricing problem. Here, we analyze the duality principle for options that depend on several assets. The asset price processes are...