In this paper we study the Lie algebra of derivations of the exterior algebra of a vector space V over a field K of characteristic ≠ 2, and the group A of automorphisms of .

L'objet de cet article est de donner quelques résultats concernant la structure des suites de fonctions mesurables sur un espace mesuré abstrait (X, ∑, μ), le théorème principal étant le suivant:

Theoreme (A). Soit (ƒn) une suite de fonctions mesurables sur un espace mesuré (X, ∑, μ) dont aucune sous-suite ne converge presque partout. Il existe alors un élément Y ∊ ∑, μ (Y) > 0, deux nombres r ∊ R, δ > 0 et une partie infinie M de N tels que, pour tout A ∊ ∑, ⊂ CF, μ(A) > 0 et pour toute partie infinie L CP.S. M (c'est-à-dire L\M est fini), on puisse trouver x et y ∊ A vérifiant ƒn(x) > r + δ et ƒn(y) < r pour une infinité d'indices n ∊ L.

Let F be a local field of characteristic zero, with q elements in its residue field, ring of integers uniformizer ωF and maximal ideal . Let GF = GL2(F). We fix Haar measures dg and dz on GF and ZF, the centre of GF, so that

meas(K) = meas

where K = GL2() is a maximal compact subgroup of GF. If T is a torus in GF we take dt to be the Haar measure on T such that

means(TM)=1

where TM denotes the maximal compact subgroup of T.

A ring with involution R is an associative ring endowed with an antiautomorphism * of period 2. One of the first commutativity results for rings with * is a theorem of S. Montgomery asserting that if R is a prime ring, in which every symmetric element s = s* is of the form s — sn(s) (n(s) ≧ 2), then either R is commutative or R is the 2 X 2 matrices over a field, which is a nice generalization of a well-known theorem of N. Jacobson on rings all of whose elements x = xn(x).

The real interpolation method is a very convenient tool in the study of imbedding relationships among Sobolev spaces and some of their fractional order generalizations, (Besov spaces, Nikolskii spaces etc.) Central to the application of these methods is the a priori determination that a given Sobolev space Wk'p(Ω) belongs to an appropriate class of spaces intermediate between two other “extreme” spaces.

In this paper we study subrings A of generated by monomials over . If A is normal and A ⊂ B integral, we can completely characterize A. If dim A = 2, we show that A is isomorphic to a subring A’ of B generated by monomials with A’ ⊂ B integral. The author became interested in these rings while studying projective modules over subrings of , For some applications, see [1].

In this article, we examine the relationship between the notions of thick groups and that of essentially finitely indecomposable (e.f.i.) groups. These groups are indecomposable objects in the quotient category of the category of abelian groups induced by the Serre-class of bounded groups.

There have been few published results concerning the relationship between the homology groups of branched and unbranched covering spaces of knots, despite the fact that these invariants are such powerful invariants for distinguishing knot types and have long been recognised as such [8]. It is well known that a simple relationship exists between these homology groups for cyclic covering spaces (see Example 3 in § 3), however for more complicated covering spaces, little has previously been known about the homology group, H1(M) of the branched covering space or about H1(U), U being the corresponding unbranched covering space, or about the relationship between these two groups.