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A refinement of Foreman's four-vertex theorem and its dual version - MaRDI portal

A refinement of Foreman's four-vertex theorem and its dual version (Q1928322)

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scientific article; zbMATH DE number 6121392
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A refinement of Foreman's four-vertex theorem and its dual version
scientific article; zbMATH DE number 6121392

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    A refinement of Foreman's four-vertex theorem and its dual version (English)
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    3 January 2013
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    The authors refine \textit{B. Foreman}'s four-vertex theorem on semi-osculating conics of a strictly convex curve \(\Gamma\) [Am. Math. Mon. 114, No. 4, 351--356 (2007; Zbl 1158.53300)]. Foreman's theorem is an application of Ghys' theorem on diffeomorphisms of \(S^{1}\). The authors deduce a projectively dual version of their refinement which is a claim about semi-osculating conics passing through two fixed points on \(\Gamma\).
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    convex curves
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    four-vertex theorem
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    semi-osculating conics
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