Abstract. If K is a field with a non-trivial non-Archimedean absolute value (multiplicative norm) | |, we describe all non-Archimedean K-algebra norms on the polynomial algebra K[X 1 , . . . , X r ] which extend | |.2000 Mathematics Subject Classification. 11S75, 11C08.
Introduction.Let K be a field with a non-trivial non-Archimedean absolute value (multiplicative norm) | |. In this paper, we study K-algebra non-Archimedean norms on K[X 1 , . . . , X r ] which extend | |. Some problems connected with the norms on p-adic vector spaces were solved by I. S. Cohen [5] and A. F. Monna [8], and then O. Goldmann and N. Iwahori were concerned in [6] with the intrinsic structure that is carried by the set of all norms on a given finite dimensional vector space over a locally compact field. When r = 1, the case of K-algebra non-Archimedean norms on K [X] which are multiplicative and extend | | has been treated in [1][2][3]. In Section 2 below we consider generalizations of the Gauss valuation. We investigate the case when a K-vector space norm is a K-algebra norm and we also address the question of when two norms are equivalent. In Section 3 we then discuss possible types of norms on K[X 1 , . . . , X r ] which extend a given non-trivial non-Archimedean absolute value on K. The completion of K[X 1 , . . . , X r ] with respect to a non-Archimedean Gauss norm is given in Section 4.There are many applications of non-Archimedean multiplicative norms on K[X 1 , . . . , X r ] in algebraic geometry where a basic tool is to describe all the absolute values on K(X 1 , . . . , X r ) which extend | |. In [7] F.-V. Kuhlmann determined which value groups and which residue fields can possibly occur in this case. In the case r = 1 the r.t. extensions | | L of | | to L = K(X) have been considered by M. Nagata [9], who