Domain 13
Sport and Competition
Sport is the natural laboratory: strictly competitive play, doping dilemmas and rule-driven equilibria are all observable.
It is also where the predictions have been tested most cleanly. Professional penalty takers and keepers mix at close to equilibrium frequencies and show near-serial independence, while amateurs show exploitable patterns — one of the better empirical vindications of mixed-strategy equilibrium anywhere. Anti-doping is enforcement design rather than moral education, and the structure says so. And competitive balance is a commons: each club maximising its own strength degrades the uncertainty that makes the league worth watching, which is the actual argument for salary caps and draft systems.
The athletes when the decisions are made by governing bodies, and the fans who supply the value of the league and hold no vote in how it is run.
What to look for
- Does the opponent gain exactly by predicting you? Then patterns are the whole risk.
- Would a clean competitor simply lose? Then it is testing, not exhortation.
- Is the league's competitiveness a shared resource being spent?
- Who benefits from the rule change, and who was consulted?
The shapes that run this field
Zero-Sum
A strictly competitive situation where one side's gain is exactly the other's loss.
Shape 01The Prisoner's Dilemma
Mutual cooperation beats mutual defection, but defecting is the better move whatever the other side does.
Shape 17The Inspection Game
A strictly competitive game with no pure equilibrium: the inspector wants to match, the evader wants to miss.
Shape 06The Commons
A rival but non-excludable resource: each user's extraction imposes a cost spread across all users.
Shape 07The Repeated Game
Repetition creates a future cost to defecting today, which can make cooperation individually rational without changing anyone's character.
In practice
Zero-Sum
A keeper who has spotted that a taker always goes the same way under pressure.
The Prisoner's Dilemma
Doping where staying clean is a pure loss unless everybody is tested.
The Commons
A league where the strongest clubs maximise their own strength and destroy the uncertainty that sells it.