Counting Curves with Tangencies

Interpreting tangency as a limit of two transverse intersections, we obtain a concrete formula to enumerate smooth degree plane curves tangent to a given line at multiple points with arbitrary order of tangency. Extending that idea, we then enumerate curves with one node with multiple tangencies to...

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Published in:Symmetry, Integrability and Geometry: Methods and Applications
Date:2025
Main Authors: Biswas, Indranil, Choudhury, Apratim, Mukherjee, Ritwik, Paul, Anantadulal
Format: Article
Language:English
Published: Інститут математики НАН України 2025
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/212879
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Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:Counting Curves with Tangencies. Indranil Biswas, Apratim Choudhury, Ritwik Mukherjee and Anantadulal Paul. SIGMA 21 (2025), 012, 50 pages

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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author Biswas, Indranil
Choudhury, Apratim
Mukherjee, Ritwik
Paul, Anantadulal
author_facet Biswas, Indranil
Choudhury, Apratim
Mukherjee, Ritwik
Paul, Anantadulal
citation_txt Counting Curves with Tangencies. Indranil Biswas, Apratim Choudhury, Ritwik Mukherjee and Anantadulal Paul. SIGMA 21 (2025), 012, 50 pages
collection DSpace DC
container_title Symmetry, Integrability and Geometry: Methods and Applications
description Interpreting tangency as a limit of two transverse intersections, we obtain a concrete formula to enumerate smooth degree plane curves tangent to a given line at multiple points with arbitrary order of tangency. Extending that idea, we then enumerate curves with one node with multiple tangencies to a given line of any order. Subsequently, we enumerate curves with one cusp that are tangent to first order to a given line at multiple points. We also present a new way to enumerate curves with one node; it is interpreted as a degeneration of a curve tangent to a given line. That method is extended to enumerate curves with two nodes, and also curves with one tacnode are enumerated. In the final part of the paper, it is shown how this idea can be applied in the setting of stable maps and perform a concrete computation to enumerate rational curves with first-order tangency. A large number of low-degree cases have been worked out explicitly.
first_indexed 2026-03-21T11:38:30Z
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institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
issn 1815-0659
language English
last_indexed 2026-03-21T11:38:30Z
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publisher Інститут математики НАН України
record_format dspace
spelling Biswas, Indranil
Choudhury, Apratim
Mukherjee, Ritwik
Paul, Anantadulal
2026-02-13T13:49:49Z
2025
Counting Curves with Tangencies. Indranil Biswas, Apratim Choudhury, Ritwik Mukherjee and Anantadulal Paul. SIGMA 21 (2025), 012, 50 pages
1815-0659
2020 Mathematics Subject Classification: 14N35; 14J45; 53D45
arXiv:2312.10759
https://nasplib.isofts.kiev.ua/handle/123456789/212879
https://doi.org/10.3842/SIGMA.2025.012
Interpreting tangency as a limit of two transverse intersections, we obtain a concrete formula to enumerate smooth degree plane curves tangent to a given line at multiple points with arbitrary order of tangency. Extending that idea, we then enumerate curves with one node with multiple tangencies to a given line of any order. Subsequently, we enumerate curves with one cusp that are tangent to first order to a given line at multiple points. We also present a new way to enumerate curves with one node; it is interpreted as a degeneration of a curve tangent to a given line. That method is extended to enumerate curves with two nodes, and also curves with one tacnode are enumerated. In the final part of the paper, it is shown how this idea can be applied in the setting of stable maps and perform a concrete computation to enumerate rational curves with first-order tangency. A large number of low-degree cases have been worked out explicitly.
We are very grateful to the referees for giving us constructive and detailed comments on the earlier version of the manuscript. We are grateful to Chitrabhanu Chaudhuri for several useful discussions related to this paper. We also thank Soumya Pal for writing a Python program to implement the Caporaso–Harris formula for verification. The first author is partially supported by a J.C. Bose Fellowship (JBR/2023/000003). The second author is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy– The Berlin Mathematics Research Center MATH+ (EXC-2046/1, project ID: 390685689). The fourth author would like to acknowledge the support of the Department of Atomic Energy, Government of India, under project no. RTI4001.
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Інститут математики НАН України
Symmetry, Integrability and Geometry: Methods and Applications
Counting Curves with Tangencies
Article
published earlier
spellingShingle Counting Curves with Tangencies
Biswas, Indranil
Choudhury, Apratim
Mukherjee, Ritwik
Paul, Anantadulal
title Counting Curves with Tangencies
title_full Counting Curves with Tangencies
title_fullStr Counting Curves with Tangencies
title_full_unstemmed Counting Curves with Tangencies
title_short Counting Curves with Tangencies
title_sort counting curves with tangencies
url https://nasplib.isofts.kiev.ua/handle/123456789/212879
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