Let be a global field of characteristic not 2, and let be an irreducible polynomial. We show that a non-degenerate quadratic space has an isometry with minimal polynomial if and only if such an isometry exists over all the completions of . This gives a partial answer to a question of Milnor.
Cite this article
Eva Bayer-Fluckiger, Isometries of quadratic spaces. J. Eur. Math. Soc. 17 (2015), no. 7, pp. 1629–1656