Interval Analysis and Calculus for Interval-Valued Functions of a Single Variable—Part II: Extremal Points, Convexity, Periodicity

We continue the presentation of new results in the calculus for interval-valued functions of a single real variable. We start here with the results presented in part I of this paper, namely, a general setting of partial orders in the space of compact intervals (in midpoint-radius representation) and...

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Main Authors: Luciano Stefanini, Laerte Sorini, Benedetta Amicizia
Format: Article
Language:English
Published: MDPI AG 2019-10-01
Series:Axioms
Subjects:
Online Access:https://www.mdpi.com/2075-1680/8/4/114
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author Luciano Stefanini
Laerte Sorini
Benedetta Amicizia
author_facet Luciano Stefanini
Laerte Sorini
Benedetta Amicizia
author_sort Luciano Stefanini
collection DOAJ
description We continue the presentation of new results in the calculus for interval-valued functions of a single real variable. We start here with the results presented in part I of this paper, namely, a general setting of partial orders in the space of compact intervals (in midpoint-radius representation) and basic results on convergence and limits, continuity, gH-differentiability, and monotonicity. We define different types of (local) minimal and maximal points and develop the basic theory for their characterization. We then consider some interesting connections with applied geometry of curves and the convexity of interval-valued functions is introduced and analyzed in detail. Further, the periodicity of interval-valued functions is described and analyzed. Several examples and pictures accompany the presentation.
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spelling doaj.art-2581ba0f72724517bb20ca902c3c35b82022-12-22T01:09:04ZengMDPI AGAxioms2075-16802019-10-018411410.3390/axioms8040114axioms8040114Interval Analysis and Calculus for Interval-Valued Functions of a Single Variable—Part II: Extremal Points, Convexity, PeriodicityLuciano Stefanini0Laerte Sorini1Benedetta Amicizia2Department of Economics, Society, Politics, University of Urbino Carlo Bo, Via A. Saffi 42, 61029 Urbino, ItalyDepartment of Economics, Society, Politics, University of Urbino Carlo Bo, Via A. Saffi 42, 61029 Urbino, ItalyDepartment of Economics, Society, Politics, University of Urbino Carlo Bo, Via A. Saffi 42, 61029 Urbino, ItalyWe continue the presentation of new results in the calculus for interval-valued functions of a single real variable. We start here with the results presented in part I of this paper, namely, a general setting of partial orders in the space of compact intervals (in midpoint-radius representation) and basic results on convergence and limits, continuity, gH-differentiability, and monotonicity. We define different types of (local) minimal and maximal points and develop the basic theory for their characterization. We then consider some interesting connections with applied geometry of curves and the convexity of interval-valued functions is introduced and analyzed in detail. Further, the periodicity of interval-valued functions is described and analyzed. Several examples and pictures accompany the presentation.https://www.mdpi.com/2075-1680/8/4/114interval-valued gh-differencecomparison indexpartial orderslattice of real intervalsconvex interval functionsperiodic interval functions
spellingShingle Luciano Stefanini
Laerte Sorini
Benedetta Amicizia
Interval Analysis and Calculus for Interval-Valued Functions of a Single Variable—Part II: Extremal Points, Convexity, Periodicity
Axioms
interval-valued gh-difference
comparison index
partial orders
lattice of real intervals
convex interval functions
periodic interval functions
title Interval Analysis and Calculus for Interval-Valued Functions of a Single Variable—Part II: Extremal Points, Convexity, Periodicity
title_full Interval Analysis and Calculus for Interval-Valued Functions of a Single Variable—Part II: Extremal Points, Convexity, Periodicity
title_fullStr Interval Analysis and Calculus for Interval-Valued Functions of a Single Variable—Part II: Extremal Points, Convexity, Periodicity
title_full_unstemmed Interval Analysis and Calculus for Interval-Valued Functions of a Single Variable—Part II: Extremal Points, Convexity, Periodicity
title_short Interval Analysis and Calculus for Interval-Valued Functions of a Single Variable—Part II: Extremal Points, Convexity, Periodicity
title_sort interval analysis and calculus for interval valued functions of a single variable part ii extremal points convexity periodicity
topic interval-valued gh-difference
comparison index
partial orders
lattice of real intervals
convex interval functions
periodic interval functions
url https://www.mdpi.com/2075-1680/8/4/114
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AT laertesorini intervalanalysisandcalculusforintervalvaluedfunctionsofasinglevariablepartiiextremalpointsconvexityperiodicity
AT benedettaamicizia intervalanalysisandcalculusforintervalvaluedfunctionsofasinglevariablepartiiextremalpointsconvexityperiodicity