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1978, Proceedings of the Edinburgh Mathematical Society
Let (S, ℳ) be a measurable space (that is, a set S in which is defined a σ-algebra ℳ of subsets) and X a locally convex space. A map M from ℳ to the family of all non-empty subsets of X is called a multimeasure iff for every sequence of disjoint sets An ɛ ℳ (n=1,2,… )with the series converges (in the sense of (6), p. 3) to M(A).
Proceedings of the American Mathematical Society, 1975
The Radon-Nikodym theorems of Segal and Zaanen are principally concerned with the classification of those measures p. for which any X« p. is given in the form (i) KA) = fAgdf or all sets A of finite p. measure. This paper is concerned with the characterization of those pairs X , p. for which the equality (i) holds for every measurable set A, and introduces a notion of compatibility that essentially solves this problem. In addition, some applications are made to Radon-Nikodym theorems for regular Borel measures.
Journal of Mathematical Analysis and Applications, 1973
Introduction. Let J be a <r-field of subsets of an abstract set M and let m(e) be a non-negative measure function defined on J. The classical Radon-Nikodym theorem [17, p. 36](1) states that, if M is the union of a countable number of sets of finite measure, then a necessary and sufficient condition for a completely additive real function R(e), defined over J, to be a Lebesgue integral (with respect to m(e)) is that R(e) be absolutely continuous relative to m(e). Our purpose is to extend this theorem to functions with values in an arbitrary Banach space and apply the resulting theorem to obtain an integral representation for the general bounded linear transformation on the space of summable functions to an arbitrary Banach space. A number of writers [4, 6, 7, 8, 11, 12, 13, 14] have obtained similar extensions; however they have all imposed restrictions either on the Banach space or on the completely additive functions considered. The theorem proved here is free of all such restrictions. It is evident that any such generalization of the Radon-Nikodym theorem will involve a corresponding generalization of the Lebesgue integral, of which there are many. A variation of an integral studied in detail by B. J. Pettis(2) will be used here. A point function x(p) defined on ¥ to a Banach space X is said to be Pettis integrable [12] provided there exists a function X(e) on J to Ï such that, for each element x of the space 3-adjoint to ï and each element e of J, the function x(x(p)) is Lebesgue integrable on the set e to the value x(X(e)). Whenever X(e) exists, it is completely additive and absolutely continuous relative to m(e). On the other hand, Pettis [12, p. 303] gave an example of a completely additive function which is absolutely continuous but is not an integral in his sense. This shows that the ordinary Pettis integral cannot appear in a general Radon-Nikodym theorem. However, without changing essentially the definition or general properties of the integral, we can enlarge the class of functions admissable for integration (so that it contains certain functions other than point functions) and thus obtain an integral which will serve our purposes. The class of functions which we will admit for integration consists of all multivalued set functions x(e) defined for elements of J having finite, nonzero Except for §5, the contents of this paper were presented to the Society, September 12, 1943. The results in §5 were presented February 27, 1944, under the title Representation of linear transformations on summable functions.
Bulletin of the Australian Mathematical Society, 2000
We prove that a Banach space X has the Radon-Nikodym property if, and only if, every weak*-lower semicontinuous convex continuous function f of X* is Gâteaux differentiable at some point of its domain with derivative in the predual space x.
Journal of Mathematical Analysis and Applications, 2013
It is well known that every bounded below and non increasing sequence in the real line converges. We give a version of this result valid in Banach spaces with the Radon-Nikodym property, thus extending a former result of A. Procházka.
Journal of the London Mathematical Society, 1968
Journal of Applied Mathematics and Stochastic Analysis, 1997
We consider a sequence{μn}of (nonnegative) measures on a general measurable space(X,ℬ). We establish sufficient conditions for setwise convergence and convergence in total variation.
Cardinal functions of partially ordered sets, topological spaces and Boolean algebras; precalibers; ideals of sets.
1998
This paper deals with the comparison of Effros measurability and scalar measurability for multifunctions whose values lie in C(X), the set of closed convex subsets of a normed linear space X. An introductory counterexample shows that, on C(X), the Effros measurability is strictly stronger than the scalar measurability. Then, we introduce the notion of countably supported subspace of C(X). After some preparatory results and examples about this class of convex subsets, we show that on an analytic countably supported subspace of C(X), the Effros and the scalar σ-fields coincide. Conversely, we show that, if on a subspace C of C(X), nonnecessarily analytic, the Effros and scalar σ-fields are identical, then C is countably supported. This leads us to exhibit and study a wide class of subspaces of C(X) both countably supported and analytic. At last, we compare our results with the already existing ones and we briefly show how our main results can be extended to the case where X is a locally convex vector space.
Functional Analysis and Its Applications, 1985
International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems, 1997
Proyecciones (Antofagasta), 2001
In this paper we define the absolutely continuous relation between nonarchimedean scalar measures and then we give and prove a version of the Radon-Nykodym Theorem in this setting. We also define the nonarchimedean vector measure and prove some results in order to prepare a version of this Theorem in a vector case.
Journal of Applied Mathematics, 2013
We consider the regularity for nonadditive measures. We prove that the non-additive measures which satisfy Egoroff's theorem and have pseudometric generating property possess Radon property (strong regularity) on a complete or a locally compact, separable metric space.
2004
Introduction. Let Σ be an algebra of subsets of a given set Ω. Assume λ1, · · · , λn, μ are (finitely additive) real-valued measures over Σ. By “linearity theorems”we mean theorems which, under suitable conditions, ensure that μ is a linear combination of the measures λi. In [M-M, Theorem 20], the authors, among many other interesting results, proved such a linearity theorem for σ-additive measures on a σ-algebra. The linearity theorem is then applied [M-M, Theorem 21] to characterize those measure games for which the core is made of measures which can be written as μ = ∑ i αiλi. We recall that measure games, which play an important role in economic theory (see [A-S], [H-N]), are cooperative games ν of the special form ν = g(λ1, · · · , λn). Let us observe that [M-M, Theorem 20], in its turn, generalizes the uniqueness theorem of [M] to a multivariate setting. In [A-B] we proved that the uniqueness theorem above cited holds true more generally for measures defined on a very general ...
2016
1 Measure Spaces 1 1.1 Algebras and σ–algebras of sets................. 1 1.1.1 Notation and preliminaries................ 1 1.1.2 Algebras and σ–algebras................. 2
Indagationes Mathematicae, 1978
Communications of the Korean Mathematical Society
In this note we present sufficient conditions for the existence of Radon-Nikodym derivatives (RND) of operator valued measures with respect to scalar measures. The RND is characterized by the Bochner integral in the strong operator topology of a strongly measurable operator valued function with respect to a nonnegative finite measure. Using this result we also obtain a characterization of compact sets in the space of operator valued measures. An extension of this result is also given using the theory of Pettis integral. These results have interesting applications in the study of evolution equations on Banach spaces driven by operator valued measures as structural controls.
Advances in Mathematics, 1992
In the theory of quasi-measures (i.e., finitely additive measures) some results have been found ensuring that, under suitable hypotheses, there exists a Radon-Nikodym derivative for pairs of quasi-measures m = (p, v): see for instance [6, 81. More recently, Greco in [S] gave a necessary and sufficient condition for the Radon-Nikodym representation of a pair of monotone set functions: Greco's theorem becomes especially meaningful when the involved set functions are finitely additive. Moreover, if the quasimeasures are continuous, Greco's characterization makes it possible to closely relate the Radon-Nikodym derivative to the geometric properties of the range R(m) of the quasi-measure m = (p, v). So, in view of a further Radon-Nikodym theorem, one may find most helpful a recent result obtained in [7] (see Lemma 1.4 below): that is, when p and v are continuous, if R(m) is closed, then it satisfies the "h.0.b." (hereditarily overlapping boundary) property. More precisely, if m(A)caR(m) for some set A, then the boundaries JR(m) and LTR(m,) partially overlap, where m,., is the quasi-measure defined as m,(B) = m(A n B) VB.
Annals of the Alexandru Ioan Cuza University - Mathematics, 2012
In this paper, we study different types of pseudo-convergences of sequences of measurable functions with respect to set-valued non-additive monotonic set functions and we establish some pseudo-versions of Egoroff theorem in the set-valued case. We also characterize important structural properties of monotone multimeasures.
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