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In algebraic geometry, the Zeuthen–Segre invariant ''I'' is an invariant of complex projective surfaces, introduced by and rediscovered by . The invariant ''I'' is defined to be ''d'' – 4''g'' – ''b'' if the surface has a pencil of curves, non-singular of genus ''g'' except for ''d'' curves with 1 ordinary node, and with ''b'' base points where the curves are non-singular and transverse. showed that the Zeuthen–Segre invariant ''I'' is χ–4, where χ is the topological Euler–Poincaré characteristic introduced by , which is equal to the Chern number ''c''2 of the surface. ==References== * * * * * * 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Zeuthen–Segre invariant」の詳細全文を読む スポンサード リンク
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