On combinatorial bounds for the total Tjurina numbers of certain curves and surfaces with isolated singularities

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1. Verfasser: Pokora, Piotr
Format: Preprint
Veröffentlicht: 2026
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author Pokora, Piotr
author_facet Pokora, Piotr
contents We investigate combinatorial bounds for the total Tjurina numbers of plane curve arrangements. Focusing on arrangements of lines and conics in $\mathbb{P}^2$ that admit only ordinary quasi-homogeneous singularities, we derive new structural inequalities governing the distribution of multiple intersection points. As a consequence, we establish sharp lower bounds for the total Tjurina numbers of free line arrangements with bounded maximal multiplicity and, more generally, for free conic-line arrangements. In particular, we show that for a free arrangement of $d$ lines and $k$ conics, the total Tjurina number grows at least quadratically in $d$ and $k$, and we demonstrate that this bound is sharp. As an application of these planar results, we construct a family of surfaces in $\mathbb{P}^{3}$ with only isolated singularities and arbitrarily large total Tjurina numbers.This provides new lower bounds for the total Tjurina numbers of certain hypersurfaces that are independent of detailed homological data.
format Preprint
id arxiv_https___arxiv_org_abs_2602_21982
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On combinatorial bounds for the total Tjurina numbers of certain curves and surfaces with isolated singularities
Pokora, Piotr
Algebraic Geometry
Combinatorics
14H50, 32S22, 14N20
We investigate combinatorial bounds for the total Tjurina numbers of plane curve arrangements. Focusing on arrangements of lines and conics in $\mathbb{P}^2$ that admit only ordinary quasi-homogeneous singularities, we derive new structural inequalities governing the distribution of multiple intersection points. As a consequence, we establish sharp lower bounds for the total Tjurina numbers of free line arrangements with bounded maximal multiplicity and, more generally, for free conic-line arrangements. In particular, we show that for a free arrangement of $d$ lines and $k$ conics, the total Tjurina number grows at least quadratically in $d$ and $k$, and we demonstrate that this bound is sharp. As an application of these planar results, we construct a family of surfaces in $\mathbb{P}^{3}$ with only isolated singularities and arbitrarily large total Tjurina numbers.This provides new lower bounds for the total Tjurina numbers of certain hypersurfaces that are independent of detailed homological data.
title On combinatorial bounds for the total Tjurina numbers of certain curves and surfaces with isolated singularities
topic Algebraic Geometry
Combinatorics
14H50, 32S22, 14N20
url https://arxiv.org/abs/2602.21982