We model and analyze strategic interaction over time in a duopolis-tic market. Each period the firms independently and simultaneously choose whether to advertise or not. Advertising increases the own immediate sales, but may also cause an externality, e.g., increase or decrease the immediate...

To analyze strategic interaction which may induce externalities, we designed Bathroom Games with frequency-dependent stage payoffs. Two people regularly use a bathroom, before leaving they can either clean up the mess made, or not. Cleaning up involves an effort, so this option always gives a...