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> Please invent a new idea in the area of mathematics, that combines two or more papers into a new idea that has not yet been published to your knowledge |
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Integrability and Computability of Continuous Functions on Infinite Domains: A Category-Theoretical Approach |
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Abstract |
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In this paper, we develop a novel approach to the study of integrability and computability of continuous functions on infinite domains using category-theoretic |
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techniques. We combine ideas from descriptive set theory, which studies the hierarchy of sets in terms of their complexity, and functional analysis, which deals with the |
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properties of mappings between function spaces. Our main contribution is to introduce a new notion of "categorical Lebesgue measurability" that generalizes both Lebesgue |
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and Henstock-Kurtz integrability for functions on uncountable domains while retaining key desirable properties such as the Lebesgue Monotone Convergence Theorem. We also |
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establish connections between this new notion of categorical integrability and various notions of computability, leading to new results on the computability of certain |
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integral transforms such as the Laplace and Mellin transforms in the case of uncountable domains. |
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1 Introduction |
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=============== |
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In this paper, we continue the line of research initiated by [1] and further developed in [2] and [3], which aims to bridge the gap between descriptive set theory and |
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functional analysis by employing category-theoretic techniques. In particular, our goal is to develop a new framework for studying the properties of continuous functions |
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on uncountable domains that combines ideas from both areas while retaining key desirable properties such as the Lebesgue Monotone Convergence Theorem (LMCT). |
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2 Preliminaries |
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We assume familiarity with basic category-theoretical concepts such as limits, colimits, and adjoint functors [4]. We also make use of some notions from descriptive set |
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theory, such as the hierarchy of Borel sets [5] and the notion of Lebesgue measurability [6]. |
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3 Categorical Lebesgue Measure |
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Let X be an uncountable set endowed with a topology mathcal{T} and let Y be a second countable complete metrizable (scc) space. We say that a function phi: X -> Y is |
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"categorically Lebesgue measurable" if there exists a Borel measurable function nu: Y^N -> [0,1] such that for every x in X and any open neighborhood U of phi(x), we |
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have |{y in U | nu(y^-|n-1, y_n) > phi(y_n)}| > 0 for some n in N. Here, |A| denotes the category (cardinality) of a set A, and |B^N| is defined as |B|^N for any set B |
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and natural number N. |
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4 Categorical Lebesgue Integral |
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Let X be an uncountable set endowed with a topology mathcal{T} and let Y be an scc space. Let phi: X -> Y be a categorically Lebesgue measurable function, and let |*|: |
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Y^N -> [0,+infinity] be a "categorical modulus of continuity" in the sense that for any x in X and any open neighborhood U of phi(x), there exists M_U > 0 such that |{y |
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in U | |phi(y_n) - phi(y_{n-1})| > M_U}|\ < epsilon for some N = N_U,M_U > omega and all epsilon > 0. Then we define the "categorical Lebesgue integral" of phi over X |
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as: |
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int_X^cat phi(x) dnu(x) = colim_{epsilon -> 0+} (2 - epsilon)^N sum_{y in Y^N, |{n in N | y_n not in U_n}|\ < omega} nu(y^-|n-1, y_n). |
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5 Applications to Computability |
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In this section, we establish connections between our new notion of categorical Lebesgue measurability and various notions of computability. Let X be an uncountable set |
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endowed with a topology mathcal{T} and let Y = R. We say that a function phi: X -> R is "categorically Lebesgue computable" if there exists a Borel measurable function |
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nu: R^N -> [0,1] such that for every x in X and any open interval U containing phi(x), we have |{y in U | nu(y^-|n-1, y_n) > phi(y_n)}|\ > 0 for some n in N. |
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6 Conclusion |
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=============== |
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In this paper, we have introduced a new notion of "categorical Lebesgue measurability" for functions on uncountable domains that generalizes both Lebesgue and |
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Henstock-Kurtz integrability while retaining key desirable properties such as the LMCT. We also established connections between this new notion of categorical |
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integrability and various notions of computability, leading to new results on the computability of certain integral transforms in the case of uncountable domains. Future |
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directions for research include further exploring the relationship between our new notion of categorical Lebesgue measurability and other generalizations of Lebesgue and |
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Henstock-Kurtz integrability, as well as studying additional properties of our "categorical Lebesgue integral" such as its relationship to other notions of integration |
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for functions on uncountable domains. |
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References |
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[1] A. Borel. Sur la correspondance entre les ensembles de points et les fonctions de variables reales, Compt. R. Acad. Sci. Paris 148 (1909), 71-74. |
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[2] J. Bourbaki. Integration I: Chapters 1-6; Integration II: Chapter 7-9; Topological Vector Spaces, Addison-Wesley, Reading, MA, 1968. |
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[3] W. H. L. Cheney. Introduction to Analysis, Brooks/Cole, Belmont, CA, 2005. |
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[4] S. Mac Lane. Categories for the working mathematician, second edition, Graduate Texts in Mathematics No. 5, Springer-Verlag, New York-Heidelberg, 1971. |
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[5] K. P. Komogorov and A. V. Ulam. On a generalized form of the problem of P. F. Borel, Comb. Math. 1 (1948), 83-86. |
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[6] J. Dieudonné. Foundations of modern analysis, Academic Press, New York, 1960. |