Higher Dimensional Spaces of Functions on the Spectrum of a Uniform Algebra

2007 ◽  
Vol 50 (1) ◽  
pp. 3-10
Author(s):  
Richard F. Basener
Keyword(s):  
Continuous Functions ◽  
Uniform Algebra ◽  
Finite Dimensional ◽  
Higher Dimensional ◽  
Spaces Of Continuous Functions ◽  
The Family ◽  
Continuous Complex ◽  
Finite Dimensional Case ◽  
Complex Valued ◽  
Shed Light

AbstractIn this paper we introduce a nested family of spaces of continuous functions defined on the spectrum of a uniform algebra. The smallest space in the family is the uniform algebra itself. In the “finite dimensional” case, from some point on the spaces will be the space of all continuous complex-valued functions on the spectrum. These spaces are defined in terms of solutions to the nonlinear Cauchy–Riemann equations as introduced by the author in 1976, so they are not generally linear spaces of functions. However, these spaces do shed light on the higher dimensional properties of a uniform algebra. In particular, these spaces are directly related to the generalized Shilov boundary of the uniform algebra (as defined by the author and, independently, by Sibony in the early 1970s).

On Operators and Distributions

1968 ◽  
Vol 11 (1) ◽  
pp. 61-64 ◽  
Author(s):  
Raimond A. Struble
Keyword(s):  
Commutative Ring ◽  
Operational Calculus ◽  
Delta Function ◽  
Generalized Functions ◽  
Dirac Delta Function ◽  
Quotient Field ◽  
Dirac Delta ◽  
The Family ◽  
Continuous Complex ◽  
Complex Valued

Mikusinski [1] has extended the operational calculus by methods which are essentially algebraic. He considers the family C of continuous complex valued functions on the half-line [0,∞). Under addition and convolution C becomes a commutative ring. Titchmarsh's theorem [2] shows that the ring has no divisors of zero and, hence, that it may be imbedded in its quotient field Q whose elements are then called operators. Included in the field are the integral, differential and translational operators of analysis as well as certain generalized functions, such as the Dirac delta function. An alternate approach [3] yields a rather interesting result which we shall now describe briefly.

Montel Algebras on the Plane

1970 ◽  
Vol 22 (1) ◽  
pp. 116-122 ◽  
Author(s):  
W. E. Meyers
Keyword(s):  
Topological Algebra ◽  
Maximum Modulus ◽  
Continuous Homomorphism ◽  
Continuous Functions ◽  
Maximum Modulus Principle ◽  
Compact Open Topology ◽  
Bounded Functions ◽  
Continuous Complex ◽  
Complex Valued

The results of Rudin in [7] show that under certain conditions, the maximum modulus principle characterizes the algebra A (G) of functions analytic on an open subset G of the plane C (see below). In [2], Birtel obtained a characterization of A(C) in terms of the Liouville theorem; he proved that every singly generated F-algebra of continuous functions on C which contains no non-constant bounded functions is isomorphic to A(C) in the compact-open topology. In this paper we show that the Montel property of the topological algebra A (G) also characterizes it. In particular, any Montel algebra A of continuous complex-valued functions on G which contains the polynomials and has continuous homomorphism space M (A) homeomorphic to G is precisely A(G).

Commutative feebly clean rings

2016 ◽  
Vol 16 (07) ◽  
pp. 1750128 ◽  
Author(s):  
Nitin Arora ◽  
S. Kundu
Keyword(s):  
Continuous Functions ◽  
Clean Rings ◽  
The Family ◽  
Complex Valued ◽  
Proper Generalization

A ring [Formula: see text] is defined to be feebly clean, if every element [Formula: see text] can be written as [Formula: see text], where [Formula: see text] is a unit and [Formula: see text], [Formula: see text] are orthogonal idempotents. Feebly clean rings generalize clean rings and are also a proper generalization of weakly clean rings. The family of all semiclean rings properly contains the family of all feebly clean rings. Further properties of feebly clean rings are studied, some of them analogous to those for clean rings. The feebly clean property is investigated for some rings of complex-valued continuous functions. Throughout, all rings are commutative with identity.

Commuting Dilations and Uniform Algebras

1990 ◽  
Vol 42 (5) ◽  
pp. 776-789 ◽  
Author(s):  
Takahiko Nakazi
Keyword(s):  
Hardy Space ◽  
Compact Hausdorff Space ◽  
Hausdorff Space ◽  
Continuous Functions ◽  
Uniform Algebra ◽  
Representing Measure ◽  
Uniform Algebras ◽  
Weak Closure ◽  
Abstract Hardy Space ◽  
Complex Valued

Let X be a compact Hausdorff space, let C(X) be the algebra of complex-valued continuous functions on X, and let A be a uniform algebra on X. Fix a nonzero complex homomorphism τ on A and a representing measure m for τ on X. The abstract Hardy space Hp = Hp(m), 1 ≤ p ≤ ∞, determined by A is defined to the closure of Lp = Lp(m) when p is finite and to be the weak*-closure of A in L∞ = L∞(m) p = ∞.

scholarly journals The Levi-Civita equation in function classes

2019 ◽  
Vol 94 (4) ◽  
pp. 689-701 ◽  
Author(s):  
Miklós Laczkovich
Keyword(s):  
Topological Semigroup ◽  
Classical Result ◽  
Continuous Functions ◽  
Exponential Polynomial ◽  
Additive Functions ◽  
Translation Invariant ◽  
Function Classes ◽  
Finite Dimensional ◽  
Special Cases ◽  
Complex Valued

Abstract Let G be an Abelian topological semigroup with unit. By a classical result (called Theorem A), if V is a finite dimensional translation invariant linear space of complex valued continuous functions defined on G, then every element of V is an exponential polynomial. More precisely, every element of V is of the form $$\sum _{i=1}^np_i \cdot m_i$$ ∑ i = 1 n p i · m i , where $$m_1 ,\ldots ,m_n$$ m 1 , … , m n are exponentials belonging to V, and $$p_1 ,\ldots ,p_n$$ p 1 , … , p n are polynomials of continuous additive functions. We generalize this statement by replacing the set of continuous functions by any algebra $${{\mathcal {A}}}$$ A of complex valued functions such that whenever an exponential m belongs to $${{\mathcal {A}}}$$ A , then $$m^{-1}\in {{\mathcal {A}}}$$ m - 1 ∈ A . As special cases we find that Theorem A remains valid even if the topology on G is not compatible with the operation on G, or if the set of continuous functions is replaced by the set of measurable functions with respect to an arbitrary $$\sigma $$ σ -algebra. We give two proofs of the result. The first is based on Theorem A. The second proof is independent, and seems to be more elementary than the existing proofs of Theorem A.

scholarly journals Separating Maps between Spaces of Vector-Valued Absolutely Continuous Functions

2010 ◽  
Vol 53 (3) ◽  
pp. 466-474 ◽  
Author(s):  
Luis Dubarbie
Keyword(s):  
Real Line ◽  
Continuous Functions ◽  
Dimensional Case ◽  
Absolutely Continuous Functions ◽  
Absolutely Continuous ◽  
Infinite Dimensional ◽  
Finite Dimensional ◽  
Finite Dimensional Case ◽  
Disjointness Preserving ◽  
Vector Valued

AbstractIn this paper we give a description of separating or disjointness preserving linear bijections on spaces of vector-valued absolutely continuous functions defined on compact subsets of the real line. We obtain that they are continuous and biseparating in the finite-dimensional case. The infinite-dimensional case is also studied.

Order of singularity applied to linear operators

1987 ◽  
Vol 106 (1-2) ◽  
pp. 103-111
Author(s):  
James E. Scroggs
Keyword(s):  
Linear Operator ◽  
Upper Bound ◽  
Jordan Block ◽  
Maximum Modulus ◽  
Linear Operators ◽  
Rate Of Growth ◽  
Finite Dimensional ◽  
Finite Dimensional Case ◽  
Norm Of The Resolvent ◽  
Complex Valued

SynopsisWe extend the notion of order of singularity for complex-valued functions, as originally set forth by Hadamard, to Banach algebra-valued functions. Restricting our attention to linear operators whose spectral radius is one, we obtain a connection between the rate of growth of the norm of iterates of a linear operator and the rate of growth of the norm of the resolvent of the operator near the spectrum of the operator. In the finite dimensional case, we obtain an upper bound on the size of the Jordan block corresponding to an eigenvalue of maximum modulus.

Continuity of Arens multiplication on the dual space of bounded uniformly continuous functions on locally compact groups and topological semigroups

1986 ◽  
Vol 99 (2) ◽  
pp. 273-283 ◽  
Author(s):  
Anthony To-Ming Lau
Keyword(s):  
Continuous Functions ◽  
Supremum Norm ◽  
Hausdorff Topology ◽  
Closed Subalgebra ◽  
Continuous Complex ◽  
Arens Multiplication ◽  
Image Position ◽  
Bounded Continuous Functions ◽  
Complex Valued ◽  
Uniformly Continuous

Let G be a topological semigroup, i.e. G is a semigroup with a Hausdorff topology such that the map (a, b) → a.b from G × G into G is continuous when G × G has the product topology. Let C(G) denote the space of complex-valued bounded continuous functions on G with the supremum norm. Let LUC (G) denote the space of bounded left uniformly continuous complex-valued functions on G i.e. all f ε C(G) such that the map a → laf of G into C(G) is continuous when C(G) has a norm topology, where (laf )(x) = f (ax) (a, x ε G). Then LUC (G) is a closed subalgebra of C(G) invariant under translations. Furthermore, if m ε LUC (G)*, f ε LUC (G), then the functionis also in LUC (G). Hence we may define a productfor n, m ε LUC(G)*. LUC (G)* with this product is a Banach algebra. Furthermore, ʘ is precisely the restriction of the Arens product defined on the second conjugate algebra l∞(G)* = l1(G)** to LUC (G)*. We refer the reader to [1] and [10] for more details.

Projective Modules over Higher-Dimensional Non-Commutative Tori

1988 ◽  
Vol 40 (2) ◽  
pp. 257-338 ◽  
Author(s):  
Marc A. Rieffel
Keyword(s):  
Ergodic Action ◽  
Identity Operator ◽  
Projective Modules ◽  
Unitary Operators ◽  
Pointwise Multiplication ◽  
Differentiable Manifolds ◽  
Higher Dimensional ◽  
Continuous Complex ◽  
Structure Constants ◽  
Complex Valued

The non-commutative tori provide probably the most accessible interesting examples of non-commutative differentiable manifolds. We can identify an ordinary n-torus Tn with its algebra, C(Tn), of continuous complex-valued functions under pointwise multiplication. But C(Tn) is the universal C*-algebra generated by n commuting unitary operators. By definition, [15, 16, 50], a non-commutative n-torus is the universal C*-algebra generated by n unitary operators which, while they need not commute, have as multiplicative commutators various fixed scalar multiples of the identity operator. As Connes has shown [8, 10], these algebras have a natural differentiable structure, defined by a natural ergodic action of Tn as a group of automorphisms. The non-commutative tori behave in inany ways like ordinary tori. For instance, it is an almost immediate consequence of the work of Pimsner and Voiculescu [37] that the K-groups of a non-commutative torus are the same as those of an ordinary torus of the same dimension. (In particular, non-commutative tori are KK-equivalent to ordinary tori by Corollary 7.5 of [52].) Furthermore, the structure constants of non-commutative tori can be continuously deformed into those for ordinary tori. (This is exploited in [17].)

On the Boundary and Tensor Product of Function Algebras

1966 ◽  
Vol 9 (1) ◽  
pp. 103-106
Author(s):  
A. S. Fox
Keyword(s):  
Tensor Product ◽  
Algebraic Structure ◽  
Compact Hausdorff Space ◽  
Closed Subset ◽  
Hausdorff Space ◽  
Maximum Modulus ◽  
Function Algebras ◽  
The Family ◽  
Continuous Complex ◽  
Complex Valued

Let be an arbitrary family of continuous complex-valued functions defined on a compact Hausdorff space X. A closed subset B ⊆ X is called a boundary for if every attains its maximum modulus at some point of B. A boundary, B, is said to be minimal if there exists no boundary for properly contained in B. It can be shown that minimal boundaries exist regardless of the algebraic structure which may possess. Under certain conditions on the family , it can be shown that a unique minimal boundary for exists. In particular, this is the case if is a subalgebra or subspace of C(X) where X is compact and Hausdorff (see for example [2]). This unique minimal boundary for an algebra of functions is called the Silov boundary of .

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