The ‘prisoner’s dilemma’ in cycling

Yesterday I was going on about some of the mathematics and science behind cycling and the Tour de France. The sport is also a great example of something from a branch of maths called Game Theory, and one particular game called “the prisoner’s dilemma”.

Take two riders in the middle of this afternoon’s stage of the Tour de France from Marseilles to La Grande-Motte. They are way ahead of the peloton. The two lads are from different teams, and are competing against each other.

Yet here they are, working together by taking turns to share the tough load of the front position – where there’s no peloton, no team mates, no shelter from the wind. In the prisoner’s dilemma game, this is called “mutual cooperation”.

If they cooperate, they both win (for the moment). But if neither of them makes an effort to stay ahead (“mutual defection”), they’ll be knackered and the peloton will soon catch up.

Or one rider does all the hard work alone (“cooperating”), keeping the two ahead of the peloton. But the second rider – the one with the easier passage in the first rider’s slipstream – can take advantage by “defecting” near the very end, and is much more likely to win. The dirty rotten scoundrel.

The prisoner’s dilemma and steroid use

The conundrums of the prisoner’s dilemma can even be seen in the take-up of banned substances in the sport…

“The prisoner’s dilemma applies to the decision whether or not to use performance enhancing drugs in athletics. Given that the drugs have an approximately equal impact on each athlete, it is to all athletes’ advantage that no athlete take the drugs (because of the side effects). However, if any one athlete takes the drugs, they will gain an advantage unless all the other athletes do the same. In that case, the advantage of taking the drugs is removed, but the disadvantages (side effects) remain.”
- from Wikipedia’s entry on the Prisoner’s Dilemma

Rémi Gaillard on tour

Talking of cheats in sport, it’s about time for another video clip from Rémi Gaillard, that French master prankster from Montpellier (“L’imposteur montpelliérain”).

One of Rémi’s favourite tricks is to sneak into various big sporting events and pretend to be a competitor. Here he’s doing a time trial in the 2007 Tour de France…

See some earlier posts about Rémi.