Explicit Free Resolutions of Tangent Cones in Affine 4-Space
Abstract
This paper is devoted to the study of minimal free resolutions of tangent cones associated with complete intersection monomial curves in affine 4-space. By applying the gluing technique for numerical semigroups, we characterize specific families of these curves where the tangent cone retains the complete intersection property. Our analysis focuses particularly on curves defined by 4-generated numerical semigroups, constructed by gluing two semigroups generated by two elements. Furthermore, we present explicit computations of their minimal free resolutions under specific conditions.
Keywords
Complete intersection, Free resolution, Gluing, Monomial curve, Tangent cone
Thanks
References
- [1] Herzog, J., Rossi, M. E., & Valla, G. (1986). On the depth of the symmetric algebra. Transactions of the American Mathematical Society, 296, 577–606. https://doi.org/10.1090/S0002-9947-1986-0846598-8
- [2] Vu, T. (2014). Periodicity of Betti numbers of monomial curves. Journal of Algebra, 418, 66–90. https://doi.org/10.1016/j.jalgebra.2014.07.007
- [3] Stamate, D. I. (2018). Betti numbers for numerical semigroup rings. In Multigraded Algebra and Applications (NSA 24, pp. 133–157). Springer International Publishing. https://doi.org/10.1007/978-3-319-90493-1_8
- [4] Herzog, J. (1970). Generators and relations of abelian semigroup rings. Manuscripta Mathematica, 3, 175–193. https://doi.org/10.1007/BF01273309
- [5] Herzog, J. (1975). When is a regular sequence super regular? Nagoya Mathematical Journal, 83, 183–195. https://doi.org/10.1017/S0027763000019474
- [6] Robbiano, L., & Valla, G. (1980). On the equations defining tangent cones. Mathematical Proceedings of the Cambridge Philosophical Society, 88(2), 281–297. https://doi.org/10.1017/S0305004100057583
- [7] Arslan, F. (1999). Cohen-Macaulayness of tangent cones. Proceedings of the American Mathematical Society, 128, 2243–2251.https://doi.org/10.1090/S0002-9939-99-05229-6
- [8] Bresinsky, H. (1975). On prime ideals with generic zero x_i=t^(n_i ). Proc. Amer. Math. Soc., 47(2) 329–332. https://www.ams.org/journals/proc/1975-047-02/S0002-9939-1975-0389912-0/
- [9] Barucci, V., Fröberg, R., & Şahin, M. (2014). On free resolutions of some semigroup rings. Journal of Pure and Applied Algebra, 218, 1107–1116.https://doi.org/10.1016/j.jpaa.2013.11.007
- [10] Şahin, M., & Şahin, N. (2019). Betti numbers for certain Cohen-Macaulay tangent cones. Bulletin of the Australian Mathematical Society, 99(1), 68–77. https://doi.org/10.1017/S0004972718000898