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On the 10-web by conics on the quartic del Pezzo surface

Luc Pirio

Abstract

We study and compare the webs $\boldsymbol{\mathcal W}_{{\rm dP}_d}$ defined by the conic fibrations on a given smooth del Pezzo surface ${\rm dP}_d$ of degree $d$ for $d=4$ and $d=5$. In a previous paper, we proved that for any positive $d\leq 6$, the web by conics $\boldsymbol{\mathcal W}_{{\rm dP}_d}$ carries a particular abelian relation ${\bf HLog}_d$, whose components all are weight $7-d$ antisymmetric hyperlogarithms. The web $\boldsymbol{\mathcal W}_{{\rm dP}_5}$ is a geometric model of the exceptional Bol's web and the relation ${\bf HLog}_5$ corresponds to the famous `Abel's identity' $(\boldsymbol{{\mathcal A}b})$ of the dilogarithm. Bol's web together with $(\boldsymbol{{\mathcal A}b})$ enjoy several remarkable properties of different kinds. We show that almost all of them admit natural generalizations to the pair $\big( \boldsymbol{\mathcal W}_{{\rm dP}_4}, {\bf HLog}_4\big)$.

On the 10-web by conics on the quartic del Pezzo surface

Abstract

We study and compare the webs defined by the conic fibrations on a given smooth del Pezzo surface of degree for and . In a previous paper, we proved that for any positive , the web by conics carries a particular abelian relation , whose components all are weight antisymmetric hyperlogarithms. The web is a geometric model of the exceptional Bol's web and the relation corresponds to the famous `Abel's identity' of the dilogarithm. Bol's web together with enjoy several remarkable properties of different kinds. We show that almost all of them admit natural generalizations to the pair .
Paper Structure (70 sections, 40 theorems, 259 equations, 2 figures, 5 tables)

This paper contains 70 sections, 40 theorems, 259 equations, 2 figures, 5 tables.

Key Result

Proposition 2.1

For $r=4,\ldots,8$, one has the following decompositions of $\mathbf C^{ \boldsymbol{\mathcal{L}}_r}$ in irreducible $W_r$-modules:See Hlog for some explanations about the notations used for the $W_r$-irreducibles.

Figures (2)

  • Figure 1: The marked Dynkin diagram of type $(D_5,\omega_4)$ on the left and the two possible types of rank four 1-marked Dynkin diagrams for the facets on the right: of type $(D_4,\omega_3)$ (up) and $(A_4,\omega_4)$ (bottom).
  • Figure 2: The marked Dynkin diagram associated to the spinor variety $\mathbb S_n^+={\rm Spin}_{2n}/P_{n-1}$.

Theorems & Definitions (60)

  • Proposition 2.1
  • Corollary 2.2
  • Corollary 2.3
  • Remark 2.4
  • Proposition 2.5
  • Lemma 2.6
  • proof
  • Lemma 2.7
  • proof
  • Lemma 2.8
  • ...and 50 more