On four-rich points defined by pencils
Fuente:
arXiv
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| Autores principales: | , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866914006844833792 |
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| author | Kokkinos, Michalis Warren, Audie |
| author_facet | Kokkinos, Michalis Warren, Audie |
| contents | In this paper we study the number of four-rich points defined by pencils of certain algebraic objects. Our main result concerns the number of four-rich points defined by four sheaves of planes; under certain non-degeneracy conditions, we prove that four sheaves of $n$ planes in $\mathbb P^3$ determine at most $O(n^{8/3})$ four-rich points. We prove this using the four dimensional Elekes-Szabó theorem. Using the same method, we prove an upper bound on the number of four-rich points determined by four sets of concentric spheres in $\mathbb C^3$. Furthermore, using the same technique with the 3-d Elekes-Szabó theorem, one can prove upper bounds on four-rich points determined by various configurations of lines/circles in the plane $\mathbb C^2$; we give one such example, involving two pencils of lines and two pencils of concentric circles in $\mathbb C^2$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_19061 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | On four-rich points defined by pencils Kokkinos, Michalis Warren, Audie Combinatorics In this paper we study the number of four-rich points defined by pencils of certain algebraic objects. Our main result concerns the number of four-rich points defined by four sheaves of planes; under certain non-degeneracy conditions, we prove that four sheaves of $n$ planes in $\mathbb P^3$ determine at most $O(n^{8/3})$ four-rich points. We prove this using the four dimensional Elekes-Szabó theorem. Using the same method, we prove an upper bound on the number of four-rich points determined by four sets of concentric spheres in $\mathbb C^3$. Furthermore, using the same technique with the 3-d Elekes-Szabó theorem, one can prove upper bounds on four-rich points determined by various configurations of lines/circles in the plane $\mathbb C^2$; we give one such example, involving two pencils of lines and two pencils of concentric circles in $\mathbb C^2$. |
| title | On four-rich points defined by pencils |
| topic | Combinatorics |
| url | https://arxiv.org/abs/2508.19061 |