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arXiv · 2009.00315

Tarski's Undefinability Theorem and Diagonal Lemma

Saeed Salehi
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Abstract

We prove the equivalence of the semantic version of Tarski's theorem on the undefinability of truth with a semantic version of the Diagonal Lemma, and also show the equivalence of syntactic Tarski's Undefinability Theorem with a weak syntactic diagonal lemma. We outline two seemingly diagonal-free proofs for these theorems from the literature, and show that syntactic Tarski's theorem can deliver G\"odel-Rosser's Incompleteness Theorem.

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Saeed Salehi. 2020-09-01. Tarski's Undefinability Theorem and Diagonal Lemma. https://doi.org/10.1093/jigpal%2Fjzab016

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