Dans le présent article, surface de Riemann ou plus simplement surface désignera une variété analytique complexe R, connexe, sans bord et de dimension 1. En terme d'une variable locale, une fonction harmonique h, définie sur R, possédant une singularité isolée au point z0, peut s'écrire comme la somme d'une fonction harmonique

et d'une partie singulière

avec αn, βn ∈ C, γ ∈ R; les deux séries sont supposées convergentes, la première pour |z – z0| suffisamment petit, la seconde pour tout z ≠ z0. Alors h(z) = u(z) + s(z). Nous dirons que la singularité de h est non-essentielle si s(z) est de la forme

et newtonienne ou logarithmique si elle s'écrit

Soit ℰn l'anneau des germes en 0 des fonctions numériques de classe C∞ dans Rn. On écrira aussi ℰx pour ℰn où x est la variable dans Rn. Désignons par Diff (n) le groupe des germes en 0 des difféomorphismes locaux τ de classe C∞ d'un voisinage de 0 dans Rn sur un voisinage de 0 tels que τ(0) = 0. Soient G un sous-groupe de Lie de Glp(R) et C∞0(Rn, G) l'ensemble des germes en 0 des applications de classe C∞ de Rn dans G.

A module M is called a serial module if the family of its submodules is linearly ordered under inclusion. A ring R is said to be serial if RR as well as RR are finite direct sums of serial modules. Nakayama [8] started the study of artinian serial rings, and he called them generalized uniserial rings. Murase [5, 6, 7] proved a number of structure theorems on generalized uniserial rings, and he described most of them in terms of quasi-matrix rings over division rings. Warfield [12] studied serial both sided noetherian rings, and showed that any such indecomposable ring is either artinian or prime. He further showed that a both sided noetherian prime serial ring is an (R:J)-block upper triangular matrix ring, where R is a discrete valuation ring with Jacobson radical J. In this paper we determine the structure of serial right noetherian rings (Theorem 2.11).

Let X be a topological space and let A ⊂ X. The character of A in X is the minimal cardinal of a base for the neighborhoods of A in X. Previous studies have shown that the character of certain subsets of X (or of X2) is related to compactness conditions on X. For example, in [12], Ginsburg proved that if the diagonal

of a space X has countable character in X2, then X is metrizable and the set of nonisolated points of X is compact. In [2], Aull showed that if every closed subset of X has countable character, then the set of nonisolated points of X is countably compact. In [18], we noted that if every closed subset of X has countable character, then MA + ┐ CH (Martin's axiom with the negation of the continuum hypothesis) implies that X is paracompact.

Cauchy spaces were introduced by Kowalsky in 1954 [9]. In that paper a first completion method for these spaces was given. In 1968 Keller [5] has shown that the Cauchy space axioms characterize the collections of Cauchy filters of uniform convergence spaces in the sense of [1]. Moreover in the completion theory of uniform convergence spaces the associated Cauchy structures play an essential role [12]. This fact explains why in the past ten years in the theory of Cauchy spaces, much attention has been given to the study of completions.

Let x = (x1, … xn) denote a point of Euclidean n space En and set Di = ∂/∂xi for i = 1, … n. Let Ω denote an exterior domain in En with smooth boundary and consider in Ω the formal elliptic problem:

1

We first consider the problem of finding nonnegative generalized solutions of (1) when τ ≧ 0, τ ≢ 0, and r(x) ≡ 0. Under more stringent conditions on the coefficients and for suitable r(x), we then show the existence of a locally bounded solution. Next, we show that, under stronger assumptions, our main criterion is also necessary. The final arguments are devoted to the consideration of illustrative examples.

Nous commençons par caractériser les algèbres infraséquentielles (cf [11]) à l'aide du rayon de régularité. Nous montrons qu'une algèbre topologique (E, τ) est infraséquentielle si, et seulement si, le rayon de régularité β est borné (i.e., l'image, par β, de tout borné de (E, τ) est un borné de R+). Nous dirons qu'une telle algèbre est β-régulière. Nous montrons qu'une algèbre β-régulière pseudo-complète (cf [3]) a tous ses caractères bornés. En fait nous obtenons que l'ensemble des caractères (algébriques) M*, de E, est équiborné. Ce résultat recouvre et généralise ceux de T. Husaïn et S.B. Ng ([12]), de G.A. Joseph ([13]) et de T. Husaïn. ([11]). Dans le cas des algèbres séquentielles pseudo-complètes, nous montrons que tout caractère est séquentiellement continu. Nous obtenons des résultats analogues sur les formes faiblement positives.

Studies of optimization problems have led in recent years to definitions of several types of generalized directional derivatives. Those derivatives of primary interest in this paper were introduced and investigated by F. M. Clarke ([5], [6], [7], [8]), J. B. Hiriart-Urruty ([12]), Lebourg ([16], [17]), R. T. Rockafellar ([23], [24], [26], [27]), Penot ([21], [22]) among others.

In an attempt to explore in more detail relationships between various types of generalized directional derivatives we discovered some unexpected results which were not observed by the above mentioned authors. We are able to give simple conditions which characterize directionally Lipschitzian functions defined on a Baire metrizable locally convex topological vector space.

A rational normal curve C of order n in [n] has, at each point P, a nest of osculating spaces

as P moves on C the [n — 2] generates a primal Dn-1 of order 2n — 2.

Hilbert [3] found the multiplicities on Dn-1 not only of the vμ+1 generated by Dμ for each lesser value of μ but also those of all submanifolds common to these various Dμ.

A surface Φ in higher space has, as explained [4] by del Pezzo, a nest of tangent spaces

of respective dimensions

they raise the problem of finding the orders of manifolds generated by them and the multiplicity of each on the higher manifolds to which it belongs: the task does not seem to have been attempted, but it may well be eased if Φ is rational and normal.

For a functor G:𝒜→𝔛 and a class 𝔇 of small categories containing the terminal category 1 we form the extension

and call G right 𝔇-pro-adjoint if and only if Pro (𝔇, G) is right adjoint. Here Pro (𝔇, 𝒜) is the completion of 𝒜with respect to 𝔇; it coincides with the usual pro-category of 𝒜 in case 𝔇 = directed sets. For this 𝔇 a full embedding Gis dense in the sense of Mardešić [11] if and only if it is right 𝔇-pro-adjoint in the above sense; this has been proved recently by Stramaccia [15]. The most important example is the embedding of the homotopy category of pointed CW-complexes into the homotopy category of pointed topological spaces (cf. [2]).

In [3], C. Davis showed that if a convex polyhedral cone C (the positive span of a finite set of vectors in Euclidean space) contains no nonzero linear subspace, then C is linearly isomorphic to the set V+ of nonnegative points in a linear subspace V of Rn. Moreover n can be taken to be the number of facets (maximal proper faces) of C.

Let R be an associative ring with 1 ≠ 0. Throughout we will be considering unitary left R-modules. Given a chain complex C over R, a free approximation of C is defined to be a free chain complex F over R together with an epimorphism τ:F → C of chain complexes with the property that H(τ):H(F) ≃ H(C). In Chapter 5, Section 2 of [3] it is proved that any chain complex C over Z has a free approximation τ:F → C. Moreover given a free approximation τ:F → C of C and any chain map f:F’ → C with F’ a free chain complex over Z, there exists a chain map φ:F’→ F with T O φ = f . Any two chain maps φ, ψ of F’ in F with T O φ = T O ψ are chain homotopic.