Singularities of the Modular Curve
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Alexander Klyachko; Orhun Kara
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Article
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2001
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Elsevier Science
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English
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Let X (l) be the modular curve, parameterizing cyclic isogenies of degree l, and Z (l) be its plane model, given by the classical modular equation l (X, >)"0. We prove that all singularities of Z (l), except two cusps, are intersections of smooth branches, and evaluate the order of contact of these