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1.
The results of this paper concern the effective cardinal structure of the subsets of [ω1]<ω1, the set of all countable subsets of ω1. The main results include dichotomy theorems and theorems which show that the effective cardinal structure is complicated.  相似文献   

2.
Let M be a smooth, compact, orientable, weakly pseudoconvex manifold of dimension 3, embedded in (N2), of codimension one or more, and endowed with the induced CR structure. Assuming that the tangential Cauchy-Riemann operator has closed range in L2(M) in order to rule out the Rossi example, we push regularity up to show has closed range in Hs(M) for all s>0. We then use the Szegö projection to show there is a smooth solution for the problem given smooth data. The results are obtained via microlocalization by piecing together estimates for functions and (0,1) forms that hold on different microlocal regions.  相似文献   

3.
Wolfgang Rump   《Journal of Algebra》2007,310(2):648-670
We associate a positive real number to any vector space K-category over a field K. Generalizing a result of Nazarova and Roiter, we show that a schurian vector space K-category is representation-finite if and only if is finite and . Such vector space categories are quasilinear, i.e. its indecomposables are simple modules over their endomorphism ring. Recently, Nazarova and Roiter introduced the concept of -faithful poset in order to clarify the structure of critical posets. Their conjecture on the precise form of -faithful posets was established by Zeldich. We generalize these results and characterize -faithful quasilinear vector space K-categories in terms of a class of hereditary algebras Hρ(D) parametrized by a skew-field D and a rational number ρ1.  相似文献   

4.
A quantized symplectic oscillator algebra of rank 1 is a PBW deformation of the smash product of the quantum plane with . We study its representation theory, and in particular, its category .  相似文献   

5.
We investigate the Lipschitz structure of p and Lp for 0<p<1 as quasi-Banach spaces and as metric spaces (with the metric induced by the p-norm) and show that they are not Lipschitz isomorphic. We prove that the -space L0 is not uniformly homeomorphic to any other Lp space, that the Lp spaces for 0<p<1 embed isometrically into one another, and reduce the problem of the uniform equivalence amongst Lp spaces to their Lipschitz equivalence as metric spaces.  相似文献   

6.
In the present paper, we investigate the convergence and the approximation order of the localized Szsz–Mirakjan operators, and obtain some new results to improve the results due to Omey [Note on operators of Szsz–Mirakjan type, J. Approx. Theory 47 (1986) 246–254].  相似文献   

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Let G=(V(G),E(G)) be a finite connected undirected graph and WV(G) a subset of vertices. We are searching for a subset XV(G) such that WX and the subgraph induced on X is a tree. -completeness results and polynomial time algorithms are given assuming that the cardinality of W is fixed or not. Besides we give complexity results when X has to induce a path or when G is a weighted graph. We also consider problems where the cardinality of X has to be minimized.  相似文献   

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We investigate the regular subquotient category introduced by Soergel in [W. Soergel, On the relation between intersection cohomology and representation theory in positive characteristic, J. Pure Appl. Algebra 152 (1–3) (2000) 311–335]. A detailed study of projective functors enables one to relate those categories for semi-simple algebraic group G and its subgroup schemata GrT. As an application we derive some information about the characters of tilting modules for G.  相似文献   

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We give a method of factoring integer matrices in into components such that the factorization is not unique unless certain information is known. In Section 2, we introduce this method of factorization and provide theorems which establish its well-definedness. In Section 3, we construct a matrix in as a product of specific types of matrices and establish an algorithm for factoring the result uniquely given an amount of information.  相似文献   

13.
We determine the essential spectra of algebraic combinations of Toeplitz operators with continuous symbol and composition operators induced by a class of linear-fractional non-automorphisms of the unit disk. The operators in question act on the Hardy space H2 on the unit disk. Our method is to realize the C*-algebra that they generate as an extension of the compact operators by a concrete C*-algebra whose invertible elements are easily characterized.  相似文献   

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We prove that fractional k-factors can be transformed among themselves by using a new adjusting operation repeatedly. We introduce, analogous to Berge’s augmenting path method in matching theory, the technique of increasing walk and derive a characterization of maximum fractional k-factors in graphs. As applications of this characterization, several results about connected fractional 1-factors are obtained.  相似文献   

17.
In this work, we establish new coincidence and common fixed point theorems for hybrid strict contraction maps by dropping the assumption “f is T-weakly commuting” for a hybrid pair (f,T) of multivalued maps in Theorem 3.10 of T. Kamran (2004) [8]. As an application, an invariant approximation result is derived.  相似文献   

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In the space of summable sequences we give an example of a one-dimensional affine subspace C such that the best Lp-approximations of 0 from C fail to converge as p↓1. We thus give an answer to this problem of convergence in infinite measure spaces.  相似文献   

20.
We complete a study of the splitting/non-splitting properties of the enumeration degrees below by proving an analog of Harrington’s non-splitting theorem for the enumeration degrees. We show how non-splitting techniques known from the study of the c.e. Turing degrees can be adapted to the enumeration degrees.  相似文献   

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