Abstract
Secant varieties are among the main protagonists in tensor decomposition, whose study involves both pure and applied mathematic areas. Grassmannians are the building blocks for skewsymmetric tensors. Although they are ubiquitous in the literature, the geometry of their secant varieties is not completely understood. In this work we determine the singular locus of the secant variety of lines to a Grassmannian Gr(k, V) using its structure as \({{\,\textrm{SL}\,}}(V)\)-variety. We solve the problems of identifiability and tangential-identifiability of points in the secant variety: as a consequence, we also determine the second Terracini locus to a Grassmannian.
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Acknowledgements
The authors warmly thank Alessandra Bernardi and Giorgio Ottaviani for the several and helpful discussions. Sincere thanks are due also to Laurent Manivel and Mateusz Michałek for their useful suggestions, as well as to the anonymous referees for the interesting and detailed remarks which allowed us to improve our work. The authors are members of the Italian GNSAGA-INdAM.
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Galgano, V., Staffolani, R. Identifiability and singular locus of secant varieties to Grassmannians. Collect. Math. (2024). https://doi.org/10.1007/s13348-023-00429-1
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DOI: https://doi.org/10.1007/s13348-023-00429-1
Keywords
- Singular locus
- Secant variety
- Grassmannian
- Homogeneous spaces
- Identifiability
- Tangential-identifiability
- Terracini locus