In logic:

- **Tarski's undefinability theorem** was obtained by Gödel before Tarski, who obtained it independently. Gödel did not publish the theorem. See Roman Murawskia (1998), "Undefinability of truth. The problem of priority: Tarski vs Gödel", *History and Philosophy of Logic*, v. 19 n. 3. pp. 153-160 

- The result sometimes known as **Gödel's diagonal lemma** was first stated by Carnap. Gödel (1934) explicitly attributed the result to Carnap (see Kurt Gödel, *Collected Works*, v. 1, p. 363).