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# Tarski's theorem

Several results obtained by the noted logician Alfred Tarski are commonly referred to as Tarski's theorem:

*Tarski's theorem on real closed fields established the decidability of the first-order theory of real numbers.
*The Knaster-Tarski theorem is a result about complete lattices.
*Tarski's undefinability theorem (also known as Tarski's truth theorem) is a semantic counterpart to Gödel's incompleteness theorem.

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