Displaying similar documents to “Optimal bound for the number of ( - 1 ) -curves on extremal rational surfaces.”

On triple curves through a rational triple point of a surface

M. R. Gonzalez-Dorrego (2006)

Annales Polonici Mathematici

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Let k be an algebraically closed field of characteristic 0. Let C be an irreducible nonsingular curve in ℙⁿ such that 3C = S ∩ F, where S is a hypersurface and F is a surface in ℙⁿ and F has rational triple points. We classify the rational triple points through which such a curve C can pass (Theorem 1.8), and give an example (1.12). We only consider reduced and irreducible surfaces.

Rational Bézier curves with infinitely many integral points

Petroula Dospra (2023)

Archivum Mathematicum

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In this paper we consider rational Bézier curves with control points having rational coordinates and rational weights, and we give necessary and sufficient conditions for such a curve to have infinitely many points with integer coefficients. Furthermore, we give algorithms for the construction of these curves and the computation of theirs points with integer coefficients.

Rational Surfaces of Kodaira Type IV

Gioia Failla, Mustapha Lahyane, Giovanni Molica Bisci (2007)

Bollettino dell'Unione Matematica Italiana

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We study the geometry of a rational surface of Kodaira type IV by giving the nature of its integral curves of self-intersection less than zero, in particular we show that they are smooth and rational. Hence, under a reasonable assumption, we prove the finite generation of its monoid of effective divisor classes and in almost all cases its anticanonical complete linear system is of projective dimension zero and of self- intersection strictly negative. Furthermore, we show that if this...

The irregularity of ruled surfaces in three dimensional projective space.

Luis Giraldo, Ignacio Sols (1998)

Collectanea Mathematica

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Let S be a ruled surface in P3 with no multiple generators. Let d and q be nonnegative integers. In this paper we determine which pairs (d,q) correspond to the degree and irregularity of a ruled surface, by considering these surfaces as curves in a smooth quadric hypersurface in P5.