Lemmings is a computer puzzle game developed by DMA Design and published by Psygnosis in 1991, in which the player has to guide a tribe of lemming creatures to safety through a hazardous landscape, by assigning them specific skills that modify their behavior in different ways. In this paper we study the optimization problem of saving the highest number of lemmings in a given landscape with a gi...

Currently, risk assessment methods for identity management systems (IDMSs) are lacking. This makes it difficult to compare IDMSs based on how they enhance privacy and security of system stakeholders. This article proposes the executable model-based risk assessment method (EM-BRAM) with the aim of addressing this challenge. The EM-BRAM identifies risk factors inherent in IDMSs and uses them as i...

For a country fractionalized in competing factions, each owning part of the stock of natural exhaustible resources, or with insecure property rights, we analyze how resources are transformed into productive capital to sustain consumption. We allow property rights to improve as the country transforms natural resources into capital. The ensuing power struggle about the control of resources is sol...

This paper analyzes the effects of employment risk and vesting rules on the substitution between 401(k)s and conventional savings. Nearly two-thirds of 401(k) plans include vesting rules, which stipulate a partial or complete forfeiture of employer-matched contributions in the event of a job loss that occurs before a service requirement is met. We characterize this risk by simulating a stochast...

Among the key barriers to investment in energy efficiency are uncertainties about attaining projected energy savings and potential disputes over stipulated savings. The fields of energy management and risk management are thus intertwined. While many technical methods have emerged to manage performance risks (e.g. building diagnostics and commissioning), financial methods are less developed in t...

We develop a tractable two-country overlapping-generations model and show that cross-country differences in financial development can explain three recent empirical patterns of international capital flows: Financial capital flows from relatively poor to relatively rich countries, while foreign direct investment flows in the opposite direction; net capital flows go from poor to rich countries; d...

The history of polio vaccination in the United States spans 50 years and includes different phases of the disease, multiple vaccines, and a sustained significant commitment of resources. We estimated cost-effectiveness ratios and assessed the net benefits of polio vaccination applicable at various points in time from the societal perspective and we discounted these back to appropriate points in...

BACKGROUND Although colorectal cancer screening is cost-effective, it requires a considerable net investment by governments or insurance companies. If screening was cost saving, governments and insurance companies might be more inclined to invest in colorectal cancer screening programs. We examined whether colorectal cancer screening would become cost saving with the widespread use of the newer...