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Giosue Muratore 
An arithmetic count of osculating lines view    
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                | Published: | November 8, 2024. |  
                | Keywords: | Osculating curves, bilinear form, Grothendieck--Witt. |  
                | Subject [2010]: | 14N15, 11E81, 14F42. |  |  | 
 |  | Abstract 
We say that a line in Pn+1k is osculating to a hypersurface Y if they meet with contact order n+1. When k=C, it is known that through a fixed point of Y, there are exactly n! of such lines. Under some parity condition on n and deg(Y), we define a quadratically enriched count of these lines over any perfect field k. The count takes values in the Grothendieck--Witt ring of quadratic forms over k and depends linearly on deg(Y).
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			  | Acknowledgements 
The author thanks Ethan Cotterill, Gabriele Degano, Stephen McKean, Kyler Siegel, and Israel Vainsencher for many useful discussions. The author also thank Michael Stillman and Matthias Zach for their computational help, and the Reviewers for taking the necessary time and effort to review the manuscript.  This work is supported by FCT - Fundaco para a Ciencia e a Tecnologia, under the project: UIDP/04561/2020 (https://doi.org/10.54499/UIDP/04561/2020).
The author is a member of GNSAGA (INdAM). 
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			  | Author information 
Giosue MuratoreCMAFcIO, 
Faculdade de Ciencias da ULisboa
 Campo Grande 1749-016 Lisboa
 Portugal
 muratore.g.e@gmail.com
 
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