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961.
蔡建平 《纯粹数学与应用数学》1999,15(1):78-81,67
研究一类高阶积分微分方程的周期边值问题,利用上下解和单调迭代法证得最大解和最小解的存在性。 相似文献
962.
Kohji Yanagawa 《Proceedings of the American Mathematical Society》1999,127(2):377-383
Let be a monomial ideal of . Bayer-Peeva-Sturmfels studied a subcomplex of the Taylor resolution, defined by a simplicial complex . They proved that if is generic (i.e., no variable appears with the same non-zero exponent in two distinct monomials which are minimal generators), then is the minimal free resolution of , where is the Scarf complex of . In this paper, we prove the following: for a generic (in the above sense) monomial ideal and each integer , there is an embedded prime of . Thus a generic monomial ideal with no embedded primes is Cohen-Macaulay (in this case, is shellable). We also study a non-generic monomial ideal whose minimal free resolution is for some . In particular, we prove that if all associated primes of have the same height, then is Cohen-Macaulay and is pure and strongly connected.
963.
Vladimir G. Pestov 《Transactions of the American Mathematical Society》1998,350(10):4149-4165
We exhibit natural classes of Polish topological groups such that every continuous action of on a compact space has a fixed point, and observe that every group with this property provides a solution (in the negative) to a 1969 problem by Robert Ellis, as the Ellis semigroup of the universal minimal -flow , being trivial, is not isomorphic with the greatest -ambit. Further refining our construction, we obtain a Polish topological group acting freely on the universal minimal flow yet such that and are not isomorphic. We also display Polish topological groups acting effectively but not freely on their universal minimal flows. In fact, we can produce examples of groups of all three types having any prescribed infinite weight. Our examples lead to dynamical conclusions for some groups of importance in analysis. For instance, both the full group of permutations of an infinite set, equipped with the pointwise topology, and the unitary group of an infinite-dimensional Hilbert space with the strong operator topology admit no free action on a compact space, and the circle forms the universal minimal flow for the topological group of orientation-preserving homeomorphisms. It also follows that a closed subgroup of an amenable topological group need not be amenable.
964.
T. Nakano 《Transactions of the American Mathematical Society》1998,350(7):2903-2924
The birational geometry of projective threefolds on which acts with 2-dimensional general orbits is studied from the viewpoint of the minimal model theory of projective threefolds. These threefolds are closely related to the minimal rational threefolds classified by Enriques, Fano and Umemura. The main results are (i) the -birational classification of such threefolds and (ii) the classification of relatively minimal models in the fixed point free cases.
965.
This paper addresses properties of maps of bounded p-variation (p>1) in the sense of N. Wiener, which are defined on a subset of the real line and take values in metric or normed spaces. We prove the structural theorem for these maps and study their continuity properties. We obtain the existence of a Hölder continuous path of minimal p-variation between two points and establish the compactness theorem relative to the p-variation, which is an analog of the well-known Helly selection principle in the theory of functions of bounded variation. We prove that the space of maps of bounded p-variation with values in a Banach space is also a Banach space. We give an example of a Hölder continuous of exponent 0<<1 set-valued map with no continuous selection. In the case p=1 we show that a compact absolutely continuous set-valued map from the compact interval into subsets of a Banach space admits an absolutely continuous selection. 相似文献
966.
We present an algorithm to compute a full set of irreducible representations of a supersolvable group over a finite field , , which is not assumed to be a splitting field of . The main subroutines of our algorithm are a modification of the algorithm of Baum and Clausen (Math. Comp. 63 (1994), 351-359) to obtain information on algebraically conjugate representations, and an effective version of Speiser's generalization of Hilbert's Theorem 90 stating that vanishes for all .
967.
Evan J. Bekos Joseph A. Gardella Jr. Frank V. Bright 《Journal of inclusion phenomena and macrocyclic chemistry》1996,26(4):185-195
The formation of-cyclodextrin (-CD) and,-cyclodextrin (-CD) inclusion complexes with free tyrosine and the tyrosine residues within two free oligopeptides were investigated using steady-state fluorescence spectroscopy. The oligopeptides consist of five amino acids (pentapeptide) and the tyrosine residues are located at then-termini. The two peptides used in this study have well-known biological functions and are known to bind selectively to specific cell receptors. Cyclodextrins were used to model this receptor-peptide (protein-ligand) interaction. Equilibrium binding constants and the enthalpy and entropy of binding were recovered. Molecular size of the tyrosine-containing species and pH (7.0 vs. 10.0) were found to have little affect on-CD binding. However, tyrosine binding to-CD was dependent on the size (free tyrosine vs. peptide), structure, and pentapeptide conformation. 相似文献
968.
969.
970.
Wuwell Liao 《Journal of statistical physics》1991,65(1-2):1-32
I derive the Kolmogorov exponents for the energy spectrum of freely-decaying, fully-developed, near-incompressible turbulence, using the methods of perturbative quantum field theory. In contrast to the approach involving Gaussian random forces, the leading-order result is determined uniquely through selfconsistency. At the first order in , I find a unique and nontrivial, IR (infrared) stable fixed-line. I show that the upper critical dimension of this system is 6, and E(k)k–2 in 3 dimensions and E(k)k–3 in 2 dimensions along this nontrivial fixed-line (at the one-loop level). 相似文献