International Society of Dynamic Games

Dynamic Games and Applications Seminar

Welfare Effects of Prey-Refuge in Fisheries

Nov 28, 2024 11:00 AM — 12:00 PM (Montreal time)

Zoom webinar link

In this paper, I use a tractable predator-prey model with endogenous harvesting to assess the impact of a prey refuge on fishery performance. Using a two-stage game framework, where the prey-refuge consistently protects a portion of the environment from predators, this paper investigates: $(i)$ how fishers modify their behavior in the presence of a prey-refuge and $(ii)$ the conditions under which the prey-refuge enhances the social welfare. The results show that reducing the intensity of species interactions via the prey-refuge diminishes fishing pressure on both prey and predator populations. Interestingly, although full prey protection maximizes the payoff from prey harvesting, it does not necessarily minimize the predator’s fishing payoff. Necessary and sufficient conditions for the existence of positive cooperative surplus are provided. Numerical examples reveal that the overall efficiency of the fishery, influenced by the prey-refuge, is highly contingent on fishers’ willingness to wait for its benefits (i.e., the discount factor). Specifically, when fishers are sufficiently patient, the prey-refuge improves social welfare. Finally, prey refuge implementation can also occur when transfers are not allowed, or when fishers coordinate their fishing strategy. This paper contributes to the fishery management literature by proposing an alternative approach that can promote efficiency through indirect incentives.

Dynamic Games and Applications Seminar

A Differential Game Approach for the Opioid Epidemic

Nov 21, 2024 11:00 AM — 12:00 PM

Zoom webinar link

Under the continuous evolution of the opioid epidemic in the US, the recent increase in addiction as well as overdose deaths due to synthetic opioids, despite increased regulations on prescription practices, warrant a more long-term forward-looking approach incorporating the strategic responses of the other stakeholders. In this work, we model the interactions between the multiple stakeholders, as a three player non-cooperative differential game between the government, health-care providers and the illicit drug providers. The state dynamics for our differential game approach is built upon a recent data-driven epidemiological model on the opioid addiction in Tennessee, extending it to include the effects of the controls or strategies of the three players. In this paper, we compute the open loop Nash Equilibrium using the minimum principle and analyze the equilibrium control strategies of the three players and compare the optimal state trajectory of the system with that of the uncontrolled system.

Dynamic Games and Applications Seminar

Comparative Dynamics in a Dynamic Oligopoly Model of Capital Accumulation

Nov 14, 2024 11:00 AM — 12:00 PM

Zoom webinar link

We revisit the generalized finite horizon dynamic oligopoly model of capital accumulation in a differential game setting and use the Oniki’s variational method to investigate the comparative dynamics of a symmetric Open-loop Nash Equilibria (OLNE) of the game with respect to several variables. We are able to trace the entire path of the comparative dynamics of these variables over the time horizon and we are thus able to determine the dynamics of the effects of changes in the parameters on the symmetric OLNE. An immediate implication of our derived comparative dynamics is that they give sharper envelope predictions than results in the existing literature. For example, we show that the initial value of a firm’s own costate variable underestimates the shadow value of the initial capital stock.