Das zariskische Diskriminantenkriterium und die Fortsetzung von Derivationen.
We prove a quantitative version of a result of Furstenberg [20] and Deligne [14] stating that the diagonal of a multivariate algebraic power series with coefficients in a field of positive characteristic is algebraic. As a consequence, we obtain that for every prime the reduction modulo of the diagonal of a multivariate algebraic power series with integer coefficients is an algebraic power series of degree at most and height at most , where is an effective constant that only depends on...
We consider subrings A of the ring of formal power series. They are defined by growth conditions on coefficients such as, for instance, Gevrey conditions. We prove a Weierstrass-Hironaka division theorem for such subrings. Moreover, given an ideal ℐ of A and a series f in A we prove the existence in A of a unique remainder r modulo ℐ. As a consequence, we get a new proof of the noetherianity of A.
Soit I un ensembre quelconque. Si M est un sous-module quelconque de A1 et N un sous-module de Mx, α-dual de M (Mazan 1976), le dual topologique de M, muni de la topologie faible, Ts(N), est, sous certaines conditions, isomorphe topologiquement à N/M⊥. Ce résultat peut s'étendre au cas où M et N sont deux modules quelconques en dualité. Cette note étudie aussi les topologies Tℑ de M, compatibles avec la dualité et introduit la notion de topologie uniforme.