The first order properties of Dedekind finite integers
Three-quantifier sentences
We give a complete proof that all 3-quantifier sentences in the primitive notation of set theory (∈, =), are decided in ZFC, and in fact in a weak fragment of ZF without the power set axiom. We obtain information concerning witnesses of 2-quantifier formulas with one free variable. There is a 5-quantifier sentence that is not decided in ZFC (see [2]).
Topological Structures On Classes I
Topological structures on classes I.
Topological Structures On Classes II
Topological structures on classes II.
Trajectories and natural numbers