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241.
We describe sufficient conditions for transferring from locally compact abelian groups to measure spaces the weak-type bounds
of maximal operators defined by multipliers of weak type. This leads to homomorphism theorems for maximal multiplier operators.
Communicated by Guido Weiss 相似文献
242.
Ulrich Kohlenbach 《Archive for Mathematical Logic》1995,34(4):279-283
It is well-known (due to C. Parsons) that the extension of primitive recursive arithmeticPRA by first-order predicate logic and the rule of
2
0
-induction
2
0
-IR is
2
0
-conservative overPRA. We show that this is no longer true in the presence of function quantifiers and quantifier-free choice for numbersAC
0,0-qf. More precisely we show that :=PRA
2 +
2
0
-IR+AC
0,0-qf proves the totality of the Ackermann function, wherePRA
2 is the extension ofPRA by number and function quantifiers and
2
0
-IR may contain function parameters.This is true even forPRA
2 +
1
0
-IR+
2
0
-IR
–+AC
0,0-qf, where
2
0
-IR
– is the restriction of
2
0
-IR without function parameters.I am grateful to an anonymous referee whose suggestions led to an improved discussion of our results 相似文献
243.
J. D. Fanning 《Aequationes Mathematicae》1994,47(2-3):143-149
Summary We prove the following two non-existence theorems for symmetric balanced ternary designs. If 1 = 1 and 0 (mod 4) then eitherV = + 1 or 42 – + 1 is a square and (42 – + 1) divides 2 – 1. If 1 = 2 thenV = ((m + 1)/2)
2 + 2,K = (m
2 + 7)/4 and = ((m – 1)/2)2 + 1 wherem 3 (mod 4). An example belonging to the latter series withV = 18 is constructed. 相似文献
244.
Relationship between tetrahedron shape measures 总被引:6,自引:0,他引:6
Tetrahedron shape measures are used for evaluating the quality of tetrahedra in finite element meshes. Three shape measures, theminimum solid angle
min
theradius ratio , and themean ratio , are discussed in this paper. A new formula for the computation of a solid angle of tetrahedron is derived. For different shape measures andv (with values 1), we establish a relationship between andv of the form
wherec
0,c
1,e
0, ande
1 are positive constants. This means that if one measure approaches zero for a poorly-shaped tetrahedron, so does the other. Combined with the property that each measure attains a maximum value only for the regular tetrahedron, this means that the shape measures are equivalent.This work was partially supported by a grant from the Natural Sciences and Engineering Research Council of Canada. 相似文献
245.
Marcel Erné 《Algebra Universalis》1994,31(1):36-65
Although the categoryCLC of complete lattices and complete homomorphisms does not possess arbitrary coproducts, we show that the tensor product introduced by Wille has the universal property of coproducts for so-called distributing families of morphisms (and only for these). As every family of morphisms into a completely distributive lattice is distributing, this includes the known fact that in the category of completely distributive lattices, arbitrary coproducts exist and coincide with the tensor products. Since the definition of tensor products is based on the notion of contexts and their concept lattices, many results on tensor products extend from complete lattices to contexts. Thus we introduce two kinds of tensor products for arbitrary families of contexts, a partial and a complete one, and establish universal properties of these tensor products.Presented by B. Jonsson. 相似文献
246.
Eike Hertel 《Geometriae Dedicata》1994,52(3):215-220
A subsetS of a metric space (X,d) is calledd-convex if for any pair of pointsx,y S each pointz X withd(x,z) +d(z,y) =d(x,y) belongs toS. We give some results and open questions concerning isometric and convexity-preserving embeddings of finite metric spaces into standard spaces and the number ofd-convex sets of a finite metric space. 相似文献
247.
Maria Rosaria Enea 《Geometriae Dedicata》1994,51(3):257-286
In this paper we develop a structure theory of algebraic right distributive quasigroups which correspond to closed and connected conjugacy classes
generating algebraic Fischer groups (in the sense of [6]) such that the mappingx x
–1
ax, fora
, is an automorphism of
(as variety). We also give examples of algebraic Fischer groups where this does not happen. It becomes clear that the class of algebraic right distributive quasigroups has nice properties concerning subquasigroups, normal subquasigroups and direct product.We give a complete classification of one- and two-dimensional as well as of minimal algebraic right distributive quasigroups. 相似文献
248.
Within the concept of projective lattice geometry we are considering the class of stable geometries which have also been introduced in [14]. The investigation of their basic properties will result in fundamental structure theorems which especially give a lattice-geometric characterization of free left modules of rank 6 over proper right Bezout rings of stable rank 2. This yields a proper generalization of previous results of ours. 相似文献
249.
Gerhard Grams 《Geometriae Dedicata》1994,50(1):87-105
In 1972 M. O'Nan proved thatL
n (q),h 3; can be characterized as a doubly-transitive groupG on a finite set , whereG
a has an Abelian normal subgroup acting not semi-regularly on -a. In the Main Theorem we show that a similar statement holds if is infinite. Our result implies O'Nan's theorem.This paper is part of the author's Ph.D. thesis written under supervision of Prof. F. G. Timmesfeld. 相似文献
250.
Ignacio Bajo 《Monatshefte für Mathematik》1994,118(1-2):1-6
Let
be a complex Lie algebra,
its underlying real Lie algebra,
a real form of
and ·, · the euclidean product induced by the real part of an hermitian inner product on
. Let aut
be the Lie algebra of skew-symmetric derivations of
. We give necessary and sufficient conditions to ensure that aut
is composed of skew-hermitian derivations. As an application, we study holomorphy in large subgroups of isometries of Lie groups. 相似文献