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181.
Jorge Picado 《Applied Categorical Structures》1994,2(3):297-313
The primary purpose of this paper is to study join-continuous frames. We present two representation theorems for them: one in terms of -subframes of complete Boolean algebras and the other in terms of certain Priestley spaces. This second representation is used to prove that the topological spaces whose frame of open sets is join-continuous are characterized by a condition which says that certain intersections of open sets are open. Finally, we show that Priestley's duality can be viewed as a partialization of the dual adjunction between the categories of, respectively, bitopological spaces and biframes, stated by B. Banaschewski, G. C. L. Brümmer and K. A. Hardie in [5].This work was partially supported by Centro de Matemáíica da Universidade de Coimbra. 相似文献
182.
183.
Oscillatory properties of a weak convergent sequence of functions bounded inL
p
, 1 ≤p ≤ ∞, may be summarized by the parametrized measure it generates. When such a measure is generated by the gradients of a sequence
of functions bounded inH
1,p
, it must have special properties. The purpose of this paper is to characterize such parametrized measures as the ones that
obey Jensen’s inequality for all quasiconvex functions with the appropriate growth at infinity. We have found subtle differences
between the casesp < ∞ andp = ∞. A consequence is that any measure determined by biting convergence is in fact generated by a sequence convergent in
a stronger sense. We also give a few applications.
Research groupTransitions and Defects in Ordered Materials, funded by the NSF, the AFOSR, and the ARO. The work of the second author is also supported by DGICYT (Spain) through “Programa
de Perfeccionamiento y Movilidad del Personal Investigador” and through Grant PB90-0245. 相似文献
184.
LetG be a nilpotent Lie group. The adapted nilpotent Fourier transform was introduced by D. Arnal and J. C. Cortet,:L(G) C
(V,L(2d
)), whereL(G) is the Schwartz space ofG andV × 2k
is aG-invariant Zariski open set ing
* the dual of the Lie algebra ofG. We prove the surjectivity of this transformation, which allows us to extend it to distribution spaces. 相似文献
185.
A. González Arias A. del Cueto J. M. Muñoz C. de Francisco L. Torres A. G. Flores M. Zazo J. Iñiguez 《Applied Physics A: Materials Science & Processing》1996,63(5):453-459
Silica may dissolve up to about 0.05 wt% in an iron excess NiZnCo spinel matrix, affecting noticeably the magnetic properties at low and high values of the applied field. The initial permeability is reduced by about 50% with the addition of only 0.1 % SiO2, while the coercivity almost triples, without noticeable changes in porosity or grain distribution. The vacancy and Fe2+ content of the sintered material also show a considerable change. The energy associated to the transformation Fe3+ Fe2+ for the samples without SiO2 was found to be 0.41–0.42 eV, while for the samples with SiO2 additions it decreased to 0.26 eV. The changes in magnetic properties are thought to be caused, more than because of the mentioned changes in ion distribution, by the stresses and defects created in the lattice due to the very small size of the Si4+ ion, which substitutes Fe3+ ions in tetrahedral sites. The transition Fe3+ Fe2+ seems to take place exclusively in the octahedral sites. 相似文献
186.
Summary It is shown that every convex set-valued function defined on a cone with a cone-basis in a real linear space with compact values in a real locally convex space has an affine selection. Similar results can be obtained for midconvex set-valued functions. 相似文献
187.
R. H. Dye 《Geometriae Dedicata》1996,60(3):289-300
A cap on a quadric is a set of its points whose pairwise joins are all chords. A cap is complete if it is not part of a larger one. The only field for which all complete quadric caps are known is GF(2). Those caps are small; the biggest for each quadric is of order the dimension of the ambient space. Apart from information about ovoids in dimensions at most 7, little else is known. Here, the evidence is increased by providing caps over GF(2), odd, which, if >1, have size of order the dimension cubed. In particular, complete caps are obtained for the quadrics Q
2m
(8), Q
+
8k+7
(8), Q
-
8k+3
(8), Q
+
8k+1
(8) and Q
-
8k+5
(8). These caps on Q
+
8k+7
(8) and Q
-
8k+3
(8) are complete on any Q
n(8) of which their quadrics are sections; so is that that of Q
4+2(8) for any Q
2n
(8) of which Q
4+2(8) is a section with the same kernel. From the correspondence with Q
2n
(8) complete caps are obtained for symplectic polarities over GF(8). 相似文献
188.
Zhen-Qing Chen 《Potential Analysis》1996,5(4):383-401
Let D be an open set in d and E be a relatively closed subset of D having zero Lebesgue measure. A necessary and sufficient integral condition is given for the Sobolev spaces W
1,2 (D) and W
1,2(D\E) to be the same. The latter is equivalent to (normally) reflecting Brownian motion (RBM) on
being indistinguishable (in distribution) from RBM on
. This integral condition is satisfied, for example, when E has zero (d–1)-dimensional Hausdorff measure. Therefore it is possible to delete from D a relatively closed subset E having positive capacity but nevertheless the RBM on
is indistinguishable from the RBM on
, or equivalently, W
1,2(D\E)=W1,2(D). An example of such kind is: D=2 and E is the Cantor set. In the proof of above mentioned results, a detailed study of RBMs on general open sets is given. In particular, a semimartingale decomposition and approximation result previously proved in [3] for RBMs on bounded open sets is extended to the case of unbounded open sets.Research supported in part by NSF Grant DMS 86-57483. 相似文献
189.
We study Sobolev embedding theorems in Lorentz-Zygmund spaces. Some limiting cases are considered.Supported by M.U.R.S.T. (1990). 相似文献
190.
An analogue of Kattov's theorem on the equality between the dimension of a Tychonov space and the analytic dimension of its ring of bounded real-valued continuous maps is established for proximity spaces and proximally continuous maps by an internal method of proof. A new kind of filter, called proximally prime filter, arises naturally as a tool in this theory. 相似文献