Using high-frequency S&P 500 data, we examined intraday efficiency by comparing the ability of several nonlinear models to forecast returns for horizons of 5, 10, 30 and 60 min. Taking into account fat tails and volatility dynamics, we compared the forecasting performance of simple random walk...

We model the organization of the firm as a type of artificial neural network in a duopoly framework. The firm plays a repeated Prisoner's Dilemma type game, but also must learn to map environmental signals to demand parameters. We study the prospects for cooperation given the need for the firm...