private String reproduce(String x, String y)
{
// n <- LENGTH(x);
// Note: this is = this.individualLength
// c <- random number from 1 to n
int c = randomOffset(individualLength);
// return APPEND(SUBSTRING(x, 1, c), SUBSTRING(y, c+1, n))
return x.substring(0, c) + y.substring(c);
}