Geometric Auslander criterion for openness of an algebraic morphism

Geometric Auslander criterion for openness of an algebraic morphism

We give a topological analogue for openness of a criterion for flatness that originates with Auslander. Over a normal base of dimension n, failure of openness is detected by a vertical component in the nth fibred power of the morphism.

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Veröffentlicht in:The Bulletin of the London Mathematical Society 2013-10, Vol.45 (5), p.1060-1064
Hauptverfasser: Adamus, Janusz, Bierstone, Edward, Milman, Pierre D.
Format: Artikel
Sprache:eng
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Zusammenfassung:We give a topological analogue for openness of a criterion for flatness that originates with Auslander. Over a normal base of dimension n, failure of openness is detected by a vertical component in the nth fibred power of the morphism.
ISSN:0024-6093
1469-2120
DOI:10.1112/blms/bdt028