In the COVID-19 pandemic, governments have, among other measures, mandated the use of COVID certificates to prove vaccination, recovery or a recent negative test, and have required individuals to show certificates to access shops, restaurants, and education or workplaces. While arguments for and...

Despite significant progress, air pollution still causes €600 billion in losses each year in the European Union - equal to 4 percent of its annual GDP. These costs stem from productivity losses such as increased absenteeism, the reduction of in-job productivity and harm to ecosystems. Air...

We provide a direct, self-contained proof for the existence of the limit, as λ→0, of the values of a λ-discounted finite two-person zero-sum stochastic game.