• Title/Summary/Keyword: Banach function algebras

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RELATIONS BETWEEN BANACH FUNCTION ALGEBRAS AND FRÉCHET FUNCTION ALGEBRAS

  • SADY, F.
    • Honam Mathematical Journal
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    • v.20 no.1
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    • pp.79-88
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    • 1998
  • In this paper we define the concept of $Fr{\acute{e}}chet$ function algebras on hemicompact spaces. So we show that under certain condition they can be represented as a projective limit of Banach function algebras. Then the class of $Fr{\acute{e}}chet$ Lipschitz algebras on hemicompact metric spaces are defined and their relations with the class of lipschitz algebras on compact metric spaces are studied.

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SUBADDITIVE SEPARATING MAPS BETWEEN REGULAR BANACH FUNCTION ALGEBRAS

  • Sady, Fereshteh;Estaremi, Yousef
    • Bulletin of the Korean Mathematical Society
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    • v.44 no.4
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    • pp.753-761
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    • 2007
  • In this note we extend the results of [3] concerning subadditive separating maps from A=C(X) to B=C(Y), for compact Hausdorff spaces X and Y, to the case where A and B are regular Banach function algebras(not necessarily unital) with A satisfying Ditkin#s condition. In particular we describe the general form of these maps and get a result on continuity of separating linear functionals.

ULTRASEPARABILITY OF CERTAIN FUNCTION ALGEBRAS

  • Hwang, Sun-Wook
    • Communications of the Korean Mathematical Society
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    • v.9 no.2
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    • pp.299-302
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    • 1994
  • Throughout this paper, let X be a compact Hausdorff space, and let C(X) (resp. $C_{R}$ /(X)) be the complex (resp. real) Banach algebra of all continuous complex-valued (resp. real-valued) functions on X with the pointwise operations and the supremum norm x. A Banach function algebra on X is a Banach algebra lying in C(X) which separates the points of X and contains the constants. A Banach function algebra on X equipped with the supremum norm is called a uniform algebra on X, that is, a uniformly closed subalgebra of C(X) which separates the points of X and contains the constants.(omitted)

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ON UNIFORMLY ULTRASEPARATING FAMILY OF FUNCTION ALGEBRAS

  • Hwang, Sunwook
    • Bulletin of the Korean Mathematical Society
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    • v.30 no.1
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    • pp.125-134
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    • 1993
  • Let X be a compact Hausdorff space, and let C(X) (resp. $C_{R}$(X)) be the complex (resp. real) Banach algebra of all continuous complex-valued(resp. real-valued) functions on X with the pointwise operations and the supremum norm x. A Banach function algebra on X is a Banach algebra lying in C(X) which separates the points of X and contains the constants. A Banach function algebra on X equipped with the supremum norm is called a uniform algebra on X, that is, a uniformly closed subalgebra of C(X) which separates the points of X and contains the constants.s.

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APPROXIMATION IN LIPSCHITZ ALGEBRAS OF INFINITELY DIFFERENTIABLE FUNCTIONS

  • Honary, T.G.;Mahyar, H.
    • Bulletin of the Korean Mathematical Society
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    • v.36 no.4
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    • pp.629-636
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    • 1999
  • We introduce Lipschitz algebras of differentiable functions of a perfect compact plane set X and extend the definition to Lipschitz algebras of infinitely differentiable functions of X. Then we define the subalgebras generated by polynomials, rational functions, and analytic functions in some neighbourhood of X, and determine the maximal ideal spaces of some of these algebras. We investigate the polynomial and rational approximation problems on certain compact sets X.

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PRIME IDEALS IN LIPSCHITZ ALGEBRAS OF FINITE DIFFERENTIABLE FUNCTIONS

  • EBADIAN, ALI
    • Honam Mathematical Journal
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    • v.22 no.1
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    • pp.21-30
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    • 2000
  • Lipschitz Algebras Lip(X, ${\alpha}$) and lip(X, ${\alpha}$) were first studied by D. R. Sherbert in 1964. B. Pavlovic in 1995 shown that in these algebras, the prime ideals containing a given prime ideal form a chain. In this paper, we show that the above property holds in $Lip^n(X,\;{\alpha})$ and $lip^n(X,\;{\alpha})$, the Lipschitz algebras of finite differentiable functions on a perfect compact place set X.

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The Maximal Ideal Space of Extended Differentiable Lipschitz Algebras

  • Abolfathi, Mohammad Ali;Ebadian, Ali
    • Kyungpook Mathematical Journal
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    • v.60 no.1
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    • pp.117-125
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    • 2020
  • In this paper, we first introduce new classes of Lipschitz algebras of infinitely differentiable functions which are extensions of the standard Lipschitz algebras of infinitely differentiable functions. Then we determine the maximal ideal space of these extended algebras. Finally, we show that if X and K are uniformly regular subsets in the complex plane, then R(X, K) is natural.

APPROXIMATE IDENTITY OF CONVOLUTION BANACH ALGEBRAS

  • Han, Hyuk
    • Journal of the Chungcheong Mathematical Society
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    • v.33 no.4
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    • pp.497-504
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    • 2020
  • A weight ω on the positive half real line [0, ∞) is a positive continuous function such that ω(s + t) ≤ ω(s)ω(t), for all s, t ∈ [0, ∞), and ω(0) = 1. The weighted convolution Banach algebra L1(ω) is the algebra of all equivalence classes of Lebesgue measurable functions f such that ‖f‖ = ∫0∞|f(t)|ω(t)dt < ∞, under pointwise addition, scalar multiplication of functions, and the convolution product (f ⁎ g)(t) = ∫0t f(t - s)g(s)ds. We give a sufficient condition on a weight function ω(t) in order that L1(ω) has a bounded approximate identity.

PROJECTIVE LIMIT OF A SEQUENCE OF BANACH FUNCTION ALGEBRAS AS A FRECHET FUNCTION ALGEBRA

  • Sady. F.
    • Bulletin of the Korean Mathematical Society
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    • v.39 no.2
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    • pp.259-267
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    • 2002
  • Let X be a hemicompact space with ($K_{n}$) as an admissible exhaustion, and for each n $\in$ N, $A_{n}$ a Banach function algebra on $K_{n}$ with respect to $\parallel.\parallel_n$ such that $A_{n+1}\midK_{n}$$\subsetA_n$ and${\parallel}f{\mid}K_n{\parallel}_n{\leq}{\parallel}f{\parallel}_{n+1}$ for all f$\in$$A_{n+1}$, We consider the subalgebra A = { f $\in$ C(X) : $\forall_n\;{\epsilon}\;\mathbb{N}$ of C(X) as a frechet function algebra and give a result related to its spectrum when each $A_{n}$ is natural. We also show that if X is moreover noncompact, then any closed subalgebra of A cannot be topologized as a regular Frechet Q-algebra. As an application, the Lipschitzalgebra of infinitely differentiable functions is considered.d.

SUPERSTABILITY OF THE p-RADICAL TRIGONOMETRIC FUNCTIONAL EQUATION

  • Kim, Gwang Hui
    • Korean Journal of Mathematics
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    • v.29 no.4
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    • pp.765-774
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    • 2021
  • In this paper, we solve and investigate the superstability of the p-radical functional equations $$f(\sqrt[p]{x^p+y^p})-f(\sqrt[p]{x^p-y^p})={\lambda}f(x)g(y),\\f(\sqrt[p]{x^p+y^p})-f(\sqrt[p]{x^p-y^p})={\lambda}g(x)f(y),$$ which is related to the trigonometric(Kim's type) functional equations, where p is an odd positive integer and f is a complex valued function. Furthermore, the results are extended to Banach algebras.