Abstract
We prove two inequalities for the complex orientations of a separating non-singular real algebraic curve in \({\mathbb {RP}}^2\) of any odd degree. We also construct a separating non-singular real (i.e., invariant under the complex conjugation) pseudoholomorphic curve in \({\mathbb {CP}}^2\) of any degree congruent to 9 mod 12 which does not satisfy one of these inequalities. Therefore the oriented isotopy type of the real locus of each of these curves is algebraically unrealizable.
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Acknowledgements
I am grateful to G. Mikhalkin, S. Nemirovski, and especially to E. Shustin for many stimulating discussions. To a great extent this work was inspired by Kummer and Shaw’s paper [KS20] though I did not use explicitly their results. I thank the referee for many useful remarks and suggestions.
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Orevkov, S.Y. Algebraically unrealizable complex orientations of plane real pseudoholomorphic curves. Geom. Funct. Anal. 31, 930–947 (2021). https://doi.org/10.1007/s00039-021-00569-1
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DOI: https://doi.org/10.1007/s00039-021-00569-1