Titre : Query Complexity and Mastermind Exposant : Carola Doerr née Winzen Résumé : After a short introduction into query complexities, we survey old and new results for a Mathematician's version of the classic 2-player board game Mastermind. For the game with $n$ positions and $k=n$ colors, we show that the Codebreaker has a winning strategy that uses only $O(n \log\log n)$ guesses for identifying the secret code. This improves the previously best known bounds of Chv\'atal (Combinatorica, 1983), Goodrich (Information Processing Letters, 2009), and others, which are all of order $n \log n$. We also present a new variant of the Mastermind game - the Hidden Permutation problem. We present matching upper and lower bounds for this problem, both for deterministic and randomized query schemes. The deterministic query complexity is $\Theta(n \log n)$, which, surprisingly, improves to $\Theta(n \log \log n)$ in the randomized setting. The result on Mastermind is joint work with Benjamin Doerr (Max Planck Institute for Informatics), Reto Spoehel (MPI Informatics), and Henning Thomas (ETH Zuerich), and is to appear at SODA 2013. The result on the Hidden Permutation problem is joint work with Peyman Afshani (MADALGO Aarhus), Manindra Agrawal (IIT Kanpur), Benjamin Doerr, Kasper Green Larsen (MADALGO Aarhus), and Kurt Mehlhorn (MPI Informatics).