COVID-19 has profoundly changed the way that we study and work. For students, especially primary and middle school students, online education has become a solution to learning problems. However, online and offline education have their own characteristics and different learning efficiencies in...

The rate of time preference is traditionally defined as the marginal rate of substitution between current and future consumption. This definition is not applicable when outcomes are indivisible. Such is the case in all discrete-choice dynamic problems which arise, for example, in modeling...

In the real world many social and economic decisions have to be made with imperfect information and uncertainty. In the past two decades, economists and mathematicians have devoted a great deal of time and effort into the study of ambiguity and much progress has been made in modeling ambiguity....