Financial markets have recently experienced a high volatility of exchange rates and of stock indices. Some economists attribute this fact in the presence of operators whose only aim is speculation and who buy and sell any financial activity without taking the long-term rationality of its price...

An important problem in environmental economics arises from te irreversibility of consuming or destroying certain resources. Extractive resources like oil are a clear example. Even for environmental resources the same seems to be true in a number of environmental cases, for example biodiversity,...