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The argument cycle and the coamoeba
Stockholm University, Faculty of Science, Department of Mathematics.
2013 (English)In: Complex Variables and Elliptic Equations, ISSN 1747-6933, Vol. 58, no 3, 373-384 p.Article in journal (Refereed) Published
Abstract [en]

We investigate the coamoeba of a complex algebraic variety V???(C*) n through the study of initial forms of the defining ideal. By use of a universal Grobner basis, we prove that the closure of the coamoeba is included in the union of coamoebas corresponding to all initial ideals. We also study complete intersections V of dimension n/2 more closely to get a lower bound for the multiplicity in V of a given point ? on the n:th torus. For this purpose, we associate a certain algebraic cycle, the argument cycle, to V and ? , and study its homology. In particular, we give a method to approximate the coamoeba when n?=?2.

Place, publisher, year, edition, pages
2013. Vol. 58, no 3, 373-384 p.
Keyword [en]
coamoeba, initial form, Grobner basis, degree of a continuous mapping, hyperplane arrangement, 14M25, 14M10
National Category
URN: urn:nbn:se:su:diva-88283DOI: 10.1080/17476933.2011.592581ISI: 000313420500007OAI: diva2:610714


Available from: 2013-03-12 Created: 2013-03-12 Last updated: 2014-05-06Bibliographically approved
In thesis
1. On the topology of the coamoeba
Open this publication in new window or tab >>On the topology of the coamoeba
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis we study the topology and geometry of the coamoeba of an algebraic variety V. The strategy that we use is to relate the coamoebas corresponding to the initial varieties of V to the coamoeba of V. We also define an analogue of the Ronkin function for the coamoeba and give an explicit formula for it.

Place, publisher, year, edition, pages
Stockholm: Department of Mathematics, Stockholm University, 2014. 36 p.
Coamoeba, Ronkin function
National Category
Mathematical Analysis
Research subject
urn:nbn:se:su:diva-103125 (URN)978-91-7447-933-1 (ISBN)
Public defence
2014-06-12, sal 14 hus 5 Kräftriket, Roslagsvägen 101, Stockholm, 13:15 (English)
Available from: 2014-05-22 Created: 2014-05-06 Last updated: 2014-05-22Bibliographically approved

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Johansson, Petter
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