6 research outputs found
Curious satisfaction classes
We present two new constructions of satisfaction/truth classes over models of
PA (Peano Arithmetic) that provide a foil to the fact that the existence of a
disjunctively correct full truth class over a model M of PA implies that
Con(PA) holds in M.Comment: 12 page
Truth, collection and deflationism in models of peano arithmetic
This thesis focuses on adding collection axioms to satisfaction classes and exploring the suitability of a formal deflationary truth predicate. Chapter 2 proves that every nonstandard, recursively saturated model of PA has a satisfaction class in which all collection axioms are true. Chapter 3 explores collection axioms for the language with the satisfaction predicate, â„’S, and proves that these entail the theory of chapter 2. This chapter then demonstrates a method of closing a model with a satisfaction class to produce a new model with an induced satisfaction class, which it is conjectured will not satisfy all Æ©1 collection axioms in â„’S. In chapter 4 we conjecture that a new formulation of Visser and Enayat's construction of extensions of models with a satisfaction classes [5] will provide elementary extensions. Using this conjecture, we demonstrate new Tarski axioms provide satisfaction classes with Æ©1 collection axioms and that these axioms can be built into the theory by reducing the language to one where formulas are stratified. Finally, in chapter 5 we argue for a new definition of a deflationary truth predicate and show that this entails there are no formalisations of a deflationary truth predicate for the full nonstandard language of arithmetic