In the simplest form of crossover (one point crossover) proceeds as
follows. First, the entire population is paired off at random to
give 
sets of potential parents. Second, pairs of solutions are
chosen to undergo crossover with probability 
. If the simulated
weighted coin toss rejects crossover for a pair, then both solutions
remain in the population unchanged. However, if it is approved, then
two new solutions are created by exchanging all the bits following a
randomly selected locus on the strings. For example, if crossover
after position 5 is proposed between solutions
1 0 0 1 1 1 0 1
and
1 1 1 1 0 0 0 0,
the resulting offspring are
1 0 0 1 1 0 0 0
and
1 1 1 1 0 1 0 1
which replace their parents in the population.
