Suppes Axiomatic Set Theory | Pdf

This ensures that a set is determined solely by its elements. There exists a set with no members. [ \exists x \forall y (y \notin x) ]

Proof : Let ( A ) and ( B ) be sets. By Pairing, ( A, B ) is a set. By Union, ( \bigcup A, B ) is a set. But ( \bigcup A, B = A \cup B ). QED. suppes axiomatic set theory pdf

The axioms are intended to be true statements about the cumulative hierarchy of sets, built in stages (ranks). Suppes’ system is essentially Zermelo–Fraenkel without the Axiom of Choice (ZF), though he discusses Choice separately. Below are the core axioms as presented in his book, rephrased for clarity. Axiom 1: Axiom of Extensionality Two sets are equal iff they have the same members. [ \forall x \forall y [ \forall z (z \in x \leftrightarrow z \in y) \rightarrow x = y ] ] This ensures that a set is determined solely by its elements

Denoted ( \mathcalP(A) ). There exists a set containing ( \emptyset ) and closed under the successor operation ( x \cup x ). Suppes states it in terms of inductive sets. This ensures an infinite set exists (necessary for arithmetic). Axiom 7: Axiom Schema of Separation (Aussonderung) For any set A and any formula ( \phi(y) ) with no free variable for A, there exists a set ( y \in A : \phi(y) ). [ \forall A \exists B \forall y (y \in B \leftrightarrow y \in A \land \phi(y)) ] By Pairing, ( A, B ) is a set

Introduction Patrick Suppes (1922–2014) was a towering figure in 20th-century philosophy of science, logic, and mathematics. His 1960 book, Axiomatic Set Theory , remains one of the most accessible yet rigorous introductions to the subject. Unlike more formalist treatments (e.g., Bernays–Gödel or Morse–Kelley), Suppes strikes a balance between philosophical motivation and technical precision. For decades, his text has been widely circulated as a PDF, serving self-learners, graduate students, and philosophers.

This avoids Russell’s paradox by restricting comprehension to subsets of existing sets. If a formula ( \phi(x, y) ) defines a functional relation on a set A, then the image of A under that function is a set. This is necessary for constructing ordinals like ( \omega + \omega ) and for proving the existence of ( \aleph_\omega ). Axiom 9: Axiom of Regularity (Foundation) Every non-empty set A has a member disjoint from A. [ \forall A [ A \neq \emptyset \rightarrow \exists x (x \in A \land x \cap A = \emptyset) ] ]

Denoted ( \emptyset ). For any sets a, b, there exists a set whose members are exactly a and b. [ \forall a \forall b \exists x \forall y (y \in x \leftrightarrow y = a \lor y = b) ]