Displaying similar documents to “A proof of Noether's formula for the arithmetic genus of an algebraic surface”

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.

A note on a theorem of Xiao Gang.

Margarita Mendes Lopes (2004)

Collectanea Mathematica

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In 1985 Xiao Gang proved that the bicanonical surface of a complex surface S of general type with p2(S) > 2 is not composed of a pencil. In this note a new proof of this theorem is presented.

Geometry of arithmetically Gorenstein curves in P.

Robin Hartshorne (2004)

Collectanea Mathematica

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We characterize the postulation character of arithmetically Gorenstein curves in P. We give conditions under which the curve can be realized in the form mH - K on some ACM surface. Finally, we complement a theorem by Watanabe by showing that any general arithmetically Gorenstein curve in P with arbitrary fixed postulation character can be obtained from a line by a series of ascending complete-intersection biliaisons.