Deforming nonnormal isolated surface singularities and constructing threefolds with P1 as exceptional set
Book chapter, 2017

Normally one assumes isolated surface singularities to be normal. The purpose of this paper is to show that it can be useful to look at nonnormal singularities. By deforming them interesting normal singularities can be constructed, such as isolated, non-Cohen-Macaulay threefold singularities. They arise by a small contraction of a smooth rational curve, whose normal bundle has a sufficiently positive subbundle. We study such singularities from their nonnormal general hyperplane section.

Nonnormal singularities

Small modifications

Simultaneous normalisation


Jan Stevens

University of Gothenburg

Chalmers, Mathematical Sciences, Algebra and geometry

Singularities and Computer Algebra: Festschrift for Gert-Martin Greuel on the Occasion of his 70th Birthday

9783319288291 (ISBN)

Subject Categories

Algebra and Logic

Geotechnical Engineering




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