Stairs of Natural Set Theories
Maydim Malkov · Pure and Applied Mathematics Journal · 2014
All contemporary set theories have intersected classes. We have built the stairs of set theories with disjoint classes. We call such theories natural. We numerate these theories by ordinals. The first set theory is T_0. We build the theory from the set N of natural numbers by using the operations of direct products and of power set by finite times. The theory contains all results of Cantor’s theory. We argue that the theory can satisfy all needs of applied mathematics. We build theory T_1 by using the universe set of all sets of T_0 and by using the operations of direct products and of power set by finite times. We build theory T_α+1 from the set of previous by using the operations of direct products and of power set by finite times, too. We build theory T_ω from the set of all sets of T_α with α < ω again by using the operations of direct products and of power set by finite times. And so on for every theory T_α, if theory T_α-1 does not exists. We use the join of all these sets to build theory T_On without operation of power set. We call members of T_On families, members of families sets, families, which are not members of families, up-sets. Families are an analog of classes of the MK set theory and up-sets are an analog of proper classes of MK theory. The theory T_On is more strong than MK theory because we use more strong axiom of comprehension. The last theory T_On+1 is external to T_On. We use T_On+1 to prove those theorems of T_On that are unproved in T_On.