# Computing Node Polynomials for Plane Curves

Abstract : According to the Göttsche conjecture (now a theorem), the degree $N^{d, \delta}$ of the Severi variety of plane curves of degree $d$ with $\delta$ nodes is given by a polynomial in $d$, provided $d$ is large enough. These "node polynomials'' $N_{\delta} (d)$ were determined by Vainsencher and Kleiman―Piene for $\delta \leq 6$ and $\delta \leq 8$, respectively. Building on ideas of Fomin and Mikhalkin, we develop an explicit algorithm for computing all node polynomials, and use it to compute $N_{\delta} (d)$ for $\delta \leq 14$. Furthermore, we improve the threshold of polynomiality and verify Göttsche's conjecture on the optimal threshold up to $\delta \leq 14$. We also determine the first 9 coefficients of $N_{\delta} (d)$, for general $\delta$, settling and extending a 1994 conjecture of Di Francesco and Itzykson.
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Cited literature [12 references]

https://hal.inria.fr/hal-01186290
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• HAL Id : hal-01186290, version 1

### Citation

Florian Block. Computing Node Polynomials for Plane Curves. 22nd International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC 2010), 2010, San Francisco, United States. pp.179-190. ⟨hal-01186290⟩

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