<i>CR</i>-Selfdual Cubic Curves

We introduce a special class of cubic curves whose defining parameter satisfies a linear or quadratic equation provided by the values of a cross ratio. There are only seven such cubics and several properties of the real cubics in this class (some of them being elliptic curves) are discussed. Using t...

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Main Authors: Mircea Crasmareanu, Cristina-Liliana Pripoae, Gabriel-Teodor Pripoae
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Mathematics
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Online Access:https://www.mdpi.com/2227-7390/13/2/317
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author Mircea Crasmareanu
Cristina-Liliana Pripoae
Gabriel-Teodor Pripoae
author_facet Mircea Crasmareanu
Cristina-Liliana Pripoae
Gabriel-Teodor Pripoae
author_sort Mircea Crasmareanu
collection DOAJ
description We introduce a special class of cubic curves whose defining parameter satisfies a linear or quadratic equation provided by the values of a cross ratio. There are only seven such cubics and several properties of the real cubics in this class (some of them being elliptic curves) are discussed. Using the Möbius transformation, we extend this self-duality and obtain new families of remarkable complex cubics. In addition, we study (from the differential geometric viewpoint) the surface parameterized by all real cubic curves and we derive its curvature functions. As a by-product, we find a new classification of real Möbius transformations and some estimates for the number of vertices of real cubic curves.
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issn 2227-7390
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spelling doaj-art-fa5861337be94f86958a175c52835bf42025-01-24T13:40:09ZengMDPI AGMathematics2227-73902025-01-0113231710.3390/math13020317<i>CR</i>-Selfdual Cubic CurvesMircea Crasmareanu0Cristina-Liliana Pripoae1Gabriel-Teodor Pripoae2Department of Mathematics, Faculty of Mathematics, “Al.I.Cuza” University, 700506 Iasi, RomaniaDepartment of Applied Mathematics, The Bucharest University of Economic Studies, Piata Romana 6, 010374 Bucharest, RomaniaDepartment of Mathematics, Faculty of Mathematics and Computer Science, University of Bucharest, Academiei 14, 010014 Bucharest, RomaniaWe introduce a special class of cubic curves whose defining parameter satisfies a linear or quadratic equation provided by the values of a cross ratio. There are only seven such cubics and several properties of the real cubics in this class (some of them being elliptic curves) are discussed. Using the Möbius transformation, we extend this self-duality and obtain new families of remarkable complex cubics. In addition, we study (from the differential geometric viewpoint) the surface parameterized by all real cubic curves and we derive its curvature functions. As a by-product, we find a new classification of real Möbius transformations and some estimates for the number of vertices of real cubic curves.https://www.mdpi.com/2227-7390/13/2/317cubic curvecross ratioCR-selfdual cubicelliptic curveJ-invariantvertices of cubic curves
spellingShingle Mircea Crasmareanu
Cristina-Liliana Pripoae
Gabriel-Teodor Pripoae
<i>CR</i>-Selfdual Cubic Curves
Mathematics
cubic curve
cross ratio
CR-selfdual cubic
elliptic curve
J-invariant
vertices of cubic curves
title <i>CR</i>-Selfdual Cubic Curves
title_full <i>CR</i>-Selfdual Cubic Curves
title_fullStr <i>CR</i>-Selfdual Cubic Curves
title_full_unstemmed <i>CR</i>-Selfdual Cubic Curves
title_short <i>CR</i>-Selfdual Cubic Curves
title_sort i cr i selfdual cubic curves
topic cubic curve
cross ratio
CR-selfdual cubic
elliptic curve
J-invariant
vertices of cubic curves
url https://www.mdpi.com/2227-7390/13/2/317
work_keys_str_mv AT mirceacrasmareanu icriselfdualcubiccurves
AT cristinalilianapripoae icriselfdualcubiccurves
AT gabrielteodorpripoae icriselfdualcubiccurves