Monday, August 24, 2009

Dawkin's weasel - it isn't that bad...


Richard Dawkins writes about his weasel alogrithm:
Although the monkey/Shakespeare model is useful for explaining the distinction between single-step selection and cumulative selection, it is misleading in important ways.

But it is useful is just another way: It helps to illustrate the importance of a sensible choice of the rate of mutation!
I calculated the expected number of generations for ten different rates of mutation per letter: 1%, 2%,..., 10%. As the graph - and the table - shows, the algorithm works best with a moderate rate of 4% or 5%.













 size of the population
2550100
1 % 534 274145
2 % 335 17596
3 % 280 14883
4 % 263 13979
5 % 266 14079
6 % 296 14682
7 % 434 15988
8 % 1394 17996
9 % 15313 229107
10 %398,256 429123


That's not much of a surprise, but contrasts with the algorithm W. Dembski declared to be the weasel: his version works best with a maximal rate of mutation...

No comments:

Post a Comment