gistfile1.rb

class Chromosome
   ...
  def self.produce_new(chrs)
    roulette(chrs)

    newchrs = []
    chrs.each do |c|
      newchrs.push(roulette(chrs))
    end
    fitnesses(newchrs)

    return newchrs
  end

  ...

The code as written in gistfile1.rb produced 2 errors when I tried to run it using v2.3.0. The first is on line 5. I had to add to_i as follows:
def fitness
@Fitness = @bitstring.to_i^0b0101
end

The second is on line 100 which reads: chrs = Chromosome.produce_new(chrs). This had to be changed to: chrs = Chromosome.produceNew(chrs), to match the definition of self.produceNew(chrs).

All in all I really enjoyed the articles. I'm am learning Ruby as a first language (not counting fortran in college) and I want to also learn how to program algorithms. I'm looking forward to your follow on article to Graph Algorithms in Ruby. I think it should be very interesting. Thank you very much for taking the time write the articles.