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Cauchy's residue theorem for a class of real valued functions

Branko Sarić (2010)

Czechoslovak Mathematical Journal

Let [ a , b ] be an interval in and let F be a real valued function defined at the endpoints of [ a , b ] and with a certain number of discontinuities within [ a , b ] . Assuming F to be differentiable on a set [ a , b ] E to the derivative f , where E is a subset of [ a , b ] at whose points F can take values ± or not be defined at all, we adopt the convention that F and f are equal to 0 at all points of E and show that 𝒦ℋ -vt a b f = F ( b ) - F ( a ) , where 𝒦ℋ -vt denotes the total value of the Kurzweil-Henstock integral. The paper ends with a few examples that illustrate...

Characterizations of Kurzweil-Henstock-Pettis integrable functions

L. Di Piazza, K. Musiał (2006)

Studia Mathematica

We prove that several results of Talagrand proved for the Pettis integral also hold for the Kurzweil-Henstock-Pettis integral. In particular the Kurzweil-Henstock-Pettis integrability can be characterized by cores of the functions and by properties of suitable operators defined by integrands.

Compact operators and integral equations in the ℋ𝒦 space

Varayu Boonpogkrong (2022)

Czechoslovak Mathematical Journal

The space ℋ𝒦 of Henstock-Kurzweil integrable functions on [ a , b ] is the uncountable union of Fréchet spaces ℋ𝒦 ( X ) . In this paper, on each Fréchet space ℋ𝒦 ( X ) , an F -norm is defined for a continuous linear operator. Hence, many important results in functional analysis, like the Banach-Steinhaus theorem, the open mapping theorem and the closed graph theorem, hold for the ℋ𝒦 ( X ) space. It is known that every control-convergent sequence in the ℋ𝒦 space always belongs to a ℋ𝒦 ( X ) space for some X . We illustrate how to apply results...

Continuity in the Alexiewicz norm

Erik Talvila (2006)

Mathematica Bohemica

If f is a Henstock-Kurzweil integrable function on the real line, the Alexiewicz norm of f is f = sup I | I f | where the supremum is taken over all intervals I . Define the translation τ x by τ x f ( y ) = f ( y - x ) . Then τ x f - f tends to 0 as x tends to 0 , i.e., f is continuous in the Alexiewicz norm. For particular functions, τ x f - f can tend to 0 arbitrarily slowly. In general, τ x f - f osc f | x | as x 0 , where osc f is the oscillation of f . It is shown that if F is a primitive of f then τ x F - F f | x | . An example shows that the function y τ x F ( y ) - F ( y ) need not be in L 1 . However, if f L 1 then τ x F - F 1 f 1 | x | ....

Controlled convergence theorems for Henstock-Kurzweil-Pettis integral on m -dimensional compact intervals

Sokol B. Kaliaj, Agron D. Tato, Fatmir D. Gumeni (2012)

Czechoslovak Mathematical Journal

In this paper we use a generalized version of absolute continuity defined by J. Kurzweil, J. Jarník, Equiintegrability and controlled convergence of Perron-type integrable functions, Real Anal. Exch. 17 (1992), 110–139. By applying uniformly this generalized version of absolute continuity to the primitives of the Henstock-Kurzweil-Pettis integrable functions, we obtain controlled convergence theorems for the Henstock-Kurzweil-Pettis integral. First, we present a controlled convergence theorem for...

Convergence theorems for the Perron integral and Sklyarenko's condition

Štefan Schwabik (1992)

Commentationes Mathematicae Universitatis Carolinae

It is shown that a uniform version of Sklyarenko's integrability condition for Perron integrals together with pointwise convergence of a sequence of integrable functions are sufficient for a convergence theorem for Perron integrals.

Convergence theorems for the PU-integral

Giuseppa Riccobono (2000)

Mathematica Bohemica

We give a definition of uniform PU-integrability for a sequence of μ -measurable real functions defined on an abstract metric space and prove that it is not equivalent to the uniform μ -integrability.

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