Full paper in PDF:
$%K. Boussaf, N. Maïnetti, and M. Hemdaoui, Tree structure on the set of multiplicative semi-norms of Krasner algebras H(D), Rev. Mat. Complut. 13 (2000), no. 1, 85109.%$

Tree Structure on the Set of Multiplicative Semi-norms of Krasner Algebras H(D)
Kamal BOUSSAF, Nicolas MAÏNETTI,
and Mohamed HEMDAOUI
Laboratoire de Mathématiques Pures
Université Blaise Pascal (Clermont-Ferrand)
Complexe Scientifique des Cézeaux
F 63177 Aubiere Cedex — France
Département de Mathématiques Pures
Université Mohammed I
Oujda — Morocco

Received: April 12, 1999
Revised: January 21, 2000

ABSTRACT

Let K  be an algebraically closed field, complete for an ultrametric absolute value, let D  be an infinite subset of K  and let H(D)  be the set of analytic elements on D  (Escassut, 1995). We denote by Mult(H(D),UD)  the set of semi-norms y of the K  -vector space H(D)  which are continuous with respect to the topology of uniform convergence on D  and which satisfy further f(fg)= f(f)f(g)  whenever f,g  (- H(D)  and fg  (-  H(D)  . This set is provided with the topology of simple convergence. By the way of a metric topology thinner than the simple convergence, we establish the equivalence between the connectedness of Mult(H(D),UD)  , the arc-connectedness of Mult(H(D), UD)  and the infraconnectedness of D  . This generalizes a result of Berkovich given on affinoid algebras (Berkovich, 1990). Next, we study the filter of neighborhoods of an element of Mult(H(D),UD)  , and we give a condition on the field K such that this filter admits a countable basis. We also prove the local arc-connectedness of Mult(H(D),U  )
           D  when D  is infraconnected. Finally, we study the metrizability of the topology of simple convergence on Mult(H(D), UD)  and we give some conditions to have an equivalence with the metric topology defined above. The fundamental tool in this survey consists of circular filters.

1991 Mathematics Subject Classification: 46S10, 11Q25.