4

3.4. Active Tactic

The fourth, active tactic involves the actions described in the Exercise.
Namely, we assume that the positive qualities of male dogs are of various values, so some dogs are more desirable than the others. When picking up a male dog we take into account the number of litters it participated in. If the best available male dog had participated in a few (less than 5) litters we freely assigned it for breeding. But if the best dog was more popular we required for it first to be checked for harmful recessive genes by combining it with an ill female dog. If all the puppies of such a pair were healthy we assumed that the male dog in question had passed the test and can be used for a higher number of breedings (up to a hundred.) If there was at least one ill dog in the test litter, we conclude that the male dog is potentially harmful, and should be excluded from further breedings. This active tactic allows to further reduce the number of ill dogs in the population.   

Figure 7 shows proportions of ill dogs in the populations ruled by tactics three and four as 0.036 and 0.022 correspondingly.