Abstract
A Taylor variety consists of all fixed order Taylor polynomials of rational functions, where the number of variables and degrees of numerators and denominators are fixed. In one variable, Taylor varieties are given by rank constraints on Hankel matrices. Inversion of the natural parametrization is known as Padé approximation. We study the dimension and defining ideals of Taylor varieties. Taylor hypersurfaces are interesting for projective geometry, since their Hessians tend to vanish. In three and more variables, there exist defective Taylor varieties whose dimension is smaller than the number of parameters. We explain this with Fröberg’s Conjecture in commutative algebra.
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References
Anick, D.: Thin algebras of embedding dimension three. J. Algebra 100, 235–259 (1986)
Baker, G., Graves-Morris, P.: Padé Approximants. Encyclopedia of Mathematics and its Applications, vol. 59. Cambridge University Press (1996)
Beckermann, B., Labahn, G.: A uniform approach for the fast computation of matrix-type Padé approximants. SIAM J. Matrix Anal Appl 15, 804–823 (1994)
Brent, R., Gustavson, F., Yun, D.: Fast solution of Toeplitz systems of equations and computation of Padé approximants. J. Algorithms 1, 259–295 (1980)
Ciliberto, C., Russo, F., Simis, A.: Homaloidal hypersurfaces and hypersurfaces with vanishing Hessian. Adv. Math. 218, 1759–1805 (2008)
Cunha, R., Mostafazadehfard, M., Ramos, Z., Simis, A.: Coordinate sections of generic Hankel matrices. J. Algebra 611, 285–319 (2022)
Eisenbud, D.: On the resiliency of determinantal ideals. Commutative algebra and combinatorics (Kyoto, 1985), 29–38, Adv. Stud. Pure Math., 11, North-Holland, (1987)
Eisenbud, D.: Linear sections of determinantal varieties. Amer. J. Math. 110, 541–575 (1988)
Fröberg, R.: An inequality for Hilbert series of graded algebras. Math. Scand. 56, 117–144 (1985)
Gondim, R., Russo, F., Staglianò, G.: Hypersurfaces with vanishing Hessian via dual Cayley trick. J. Pure Appl. Algebra 224, 1215–1240 (2020)
Hermite, C.: Sur la généralisation des fractions continues algébriques. Annali di Matematica Pura ed Applicata 1867–1897(21), 289–308 (1893)
Naldi, S., Neiger, V.: A divide-and-conquer algorithm for computing Gröbner bases of syzygies in finite dimension. Proceedings of the 45th International Symposium on Symbolic and Algebraic Computation, pp. 380–387 (2020)
Nenashev, G.: A note on Fröberg’s conjecture for forms of equal degrees. C. R. Math. Acad. Sci. Paris 355, 272–276 (2017)
Nicklasson, L.: On the Hilbert series of ideals generated by generic forms. Comm. Algebra 45, 3390–3395 (2017)
Padé, H.: Sur la généralisation des fractions continues algébriques. Journal de Mathématiques Pures et Appliquées 10, 291–329 (1894)
Pardue, K.: Generic sequences of polynomials. J. Algebra 324, 579–590 (2010)
Perazzo, U.: Sulle varietá cubiche la cui hessiana svanisce identicamente. G. Mat. Battaglini 38, 337–354 (1900)
Russo, F.: On the Geometry of Some Special Projective Varieties. Lecture Notes of the Unione Matematica Italiana, 18, Springer, Cham (2016)
Valla, G.: Problems and Results on Hilbert Functions of Graded Algebras. Six Lectures on Commutative Algebra (Bellaterra, 1996), Progr. Math., 166, Birkhäuser, Basel (1998)
Acknowledgements
Aldo Conca is supported by the project PRIN 2020355B8Y “Squarefree Gröbner degenerations, special varieties and related topics” and from GNSAGA-INdAM and was supported in part by the MIUR Excellence Department Project awarded to Dipartimento di Matematica, Università di Genova, CUP D33C23001110001. Giorgio Ottaviani is member of GNSAGA-INdAM. Simone Naldi is supported by the ANR project ANR21-CE48-0006-01 “HYPERSPACE”.
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Conca, A., Naldi, S., Ottaviani, G. et al. Taylor Polynomials of Rational Functions. Acta Math Vietnam 49, 19–37 (2024). https://doi.org/10.1007/s40306-023-00514-4
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DOI: https://doi.org/10.1007/s40306-023-00514-4
Keywords
- Taylor polynomials
- Determinantal varieties
- Hankel matrices
- Padé approximation
- Fröberg’s conjecture
- Hessians