A version of the Stone-Weierstrass theorem in fuzzy analysis

Let C ( K , E 1 ) be the space of continuous functions defined between a compact Hausdorff space K and the space of fuzzy numbers E 1 endowed with the supremum metric. We provide a set of sufficient conditions on a subspace of C ( K , E 1 ) in order that it be dense. We also obtain a similar result for interpolating families of C ( K , E 1 ) . As a corollary of the above results we prove that certain fuzzy-number-valued neural networks can approximate any continuous fuzzy-number-valued function defined on a compact subspace of R

Completeness, metrizability and compactness in spaces of fuzzy-number-valued functions

Fuzzy-number-valued functions, that is, functions defined on a topological space taking values in the space of fuzzy numbers, play a central role in the development of Fuzzy Analysis. In this paper we study completeness, metrizability and compactness of spaces of continuous fuzzy-number-valued functions

Sequentially compact subsets and monotone functions: An application to fuzzy theory

Let (X,<,τO) be a first countable compact linearly ordered topological space. If (Y,D) is a uniform sequentially compact linearly ordered space with weight less than the splitting number s, then we characterize the sequentially compact subsets of the space M(X,Y) of all monotone functions from X into Y endowed with the topology of the uniform convergence induced by the uniformity D. In particular, our results are applied to identify the compact subsets of M([0,1],Y) for a wide class of linearly ordered topological spaces, including Y=R. This allows us to provide a characterization of the compact subsets of an extended version of the fuzzy number space (with the supremum metric) where the reals are replaced by certain linearly ordered topological spaces, which corrects some characterizations which appear in the literature. Since fuzzy analysis is based on the notion of fuzzy number just as much as classical analysis is based on the concept of real number, our results open new possibilities of research in this field

Bilinear isometries on spaces of vector-valued continuous functions

Let X, Y, Z be compact Hausdorff spaces and let E1, E2, E3 be Banach spaces. If T:C(X,E1)×C(Y,E2)→C(Z,E3) is a bilinear isometry which is stable on constants and E3 is strictly convex, then there exist a nonempty subset Z0 of Z, a surjective continuous mapping h:Z0→X×Y and a continuous function ω:Z0→Bil(E1×E2,E3) such that T(f,g)(z)=ω(z)(f(πX(h(z))),g(πY(h(z)))) for all z∈Z0 and every pair (f,g)∈C(X,E1)×C(Y,E2). This result generalizes the main theorems in Cambern (1978) [2] and Moreno and Rodríguez (2005) [7]

Multilinear isometries on function algebras

Let be function algebras (or more generally, dense subspaces of uniformly closed function algebras) on locally compact Hausdorff spaces , respectively, and let Z be a locally compact Hausdorff space. A -linear map is called a multilinear (or k-linear) isometry if (Formula presented.) Based on a new version of the additive Bishop’s Lemma, we provide a weighted composition characterization of such maps. These results generalize the well-known Holsztyński’s theorem and the bilinear version of this theorem provided in Moreno and Rodríguez [Studia Math. 2005;166:83–91] by a different approach.Research of J.J. Font and M. Sanchis was partially supported by the Spanish Ministry of Science and Education [grant number MTM2011-23118], and by Bancaixa [Projecte P11B2011-30]

A version of Stone-Weierstrass theorem in Fuzzy Analysis

[EN] Let C(K, E1) be the space of continuous functions defined between a compact Hausdorff space K and the space of fuzzy numbers E1 endowed with the supremum metric. We provide a sufficient set of conditions on a subspace of C(K, E1) in order that it be dense. We also obtain a similar result for interpolating families of C(K, E1).This research is supported by Spanish Government (MTM2016-77143-P), Universitat Jaume I (Projecte P1-1B2014-35) and Generalitat Valenciana (Projecte AICO/2016/030).Font, JJ.; Sanchis, D.; Sanchis, M. (2017). A version of Stone-Weierstrass theorem in Fuzzy Analysis. En Proceedings of the Workshop on Applied Topological Structures. Editorial Universitat Politècnica de València. 41-46. http://hdl.handle.net/10251/128026OCS414

A Generalized Mazur-Ulam Theorem for Fuzzy Normed Spaces

We introduce fuzzy norm-preserving maps, which generalize the concept of fuzzy isometry. Based on the ideas from Vogt, 1973, and V¨ais¨al¨a, 2003, we provide the following generalized version of theMazur-Ulam theorem in the fuzzy context: let ���, ��� be fuzzy normed spaces and let ��� : ��� → ��� be a fuzzy norm-preserving surjection satisfying ���(0) = 0. Then ��� is additive

Mazur-Ulam type theorems for fuzzy normed spaces

In this paper, we provide Mazur-Ulam type results for (not necessarily surjective) maps preserving equality of fuzzy distance defined between two fuzzy normed spaces. Our main goal is to study the additivity of such generalizations of fuzzy isometries. As in the classical case, the fuzzy strict convexity of the target space will play an important role