One-third hypothesis the cohesiveness of the group that is one-third. According to the binomial coefficient a group of size r occurs in a population of size n in formula_1 ways. Because each group of size r can dissolve in "2" subgroups, the total number of ways all groups of size r can emerge and dissolve equals "3", in keeping with the summation: formula_2 Said otherwise, large groups close to two-thirds of the population will be more likely than any other groups to dissolve into splinter groups. A corollary of this consideration is that much smaller groups will be the ones most likely
Rule of thirds (diving) Rule of thirds (diving) In scuba diving, the rule of thirds is a rule of thumb used by divers to plan dives so they have enough breathing gas remaining in their diving cylinder at the end of the dive to be able to complete the dive safely. This rule generally only applies to diving in overhead environments, such as caves and wrecks, where a direct ascent to the surface is impossible and the divers must return the way they came. For divers following the rule, one third of the gas supply is planned for the outward journey, one third is