Monodromy of rational curves on toric surfaces
For an ample line bundle L on a complete toric surface X, we consider the subset VL⊂|L| of irreducible, nodal, rational curves contained in the smooth locus of X. We study the monodromy map from the fundamental group of VL to the permutation group on the set of nodes of a reference curve C∈VL. We id...
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Veröffentlicht in: | Journal of topology 2020-12, Vol.13 (4), p.1658-1681 |
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Sprache: | eng |
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Zusammenfassung: | For an ample line bundle L on a complete toric surface X, we consider the subset VL⊂|L| of irreducible, nodal, rational curves contained in the smooth locus of X. We study the monodromy map from the fundamental group of VL to the permutation group on the set of nodes of a reference curve C∈VL. We identify a certain obstruction map ΨX defined on the set of nodes of C and show that the image of the monodromy is exactly the group of deck transformations of ΨX, provided that L is sufficiently big (in the sense we make precise below). Along the way, we construct a handy tool to compute the image of the monodromy for any pair (X,L). Eventually, we present a family of pairs (X,L) with small L and for which the image of the monodromy is strictly smaller than expected. |
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ISSN: | 1753-8416 1753-8424 1753-8424 |
DOI: | 10.1112/topo.12171 |