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  Topic: Evolutionary Computation, Stuff that drives AEs nuts< Next Oldest | Next Newest >  
Zachriel



Posts: 2723
Joined: Sep. 2006

(Permalink) Posted: June 18 2009,18:58   

Quote (Bob O'H @ June 18 2009,01:58)
   
Quote
Unrestricted probability selection:

c...     For unrestricted probability selection, divide the phenotypic  
c...     fitness by a uniformly distributed random number prior to
c...     ranking and truncation.  This procedure allows the probability
c...     of surviving and reproducing in the next generation to be
c...     directly related to phenotypic fitness and also for the correct
c...     number of individuals to be eliminated to maintain a constant
c...     population size.

        do i=1,total_offspring
           work_fitness(i) = work_fitness(i)/(randomnum(1) + 1.d-15)
        end do


Divide by randomnum as well as add non-heritable noise to the phenotype?

:-)  No idea what's going on.

Basically, he is applying reductions in heritability twice. The heritability function itself, and then this random procedure for selecting reproductive winners by re-ranking them before truncation and passing to the next generation. We could modify the divisor to some function(randomnum) and adjust the degree and type of randomness for picking winners {something like randomnum^N}. It's just another way of introducing random factors into the choice of winners and losers which should already have been accounted for in the heritability function.

The net result is a significant reduction in the effect of selection.

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You never step on the same tard twice—for it's not the same tard and you're not the same person.

   
  419 replies since Mar. 17 2009,11:00 < Next Oldest | Next Newest >  

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