Displaying similar documents to “The number of conics tangent to five given conics: the real case.”

Felix Klein's paper on real flexes vindicated

Felice Ronga (1998)

Banach Center Publications

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In a paper written in 1876 [4], Felix Klein gave a formula relating the number of real flexes of a generic real plane projective curve to the number of real bitangents at non-real points and the degree, which shows in particular that the number of real flexes cannot exceed one third of the total number of flexes. We show that Klein's arguments can be made rigorous using a little of the theory of singularities of maps, justifying in particular his resort to explicit examples. ...

Curves on a smooth quadric.

S. Giuffrida, R. Maggioni (2003)

Collectanea Mathematica

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We associate to every curve on a smooth quadric a polynomial equation that defines it as a divisor; this polynomial is defined through a matrix. In this way we can study several properties of these curves; in particular we can give a geometrical meaning to the rank of the matrix which defines the curve.