Simplified presentation conjecture for tangent conic-line arrangements

Let SS be a conic-line arrangement with two tangent conics and nn lines which are tangent to these conics. Assume that the tangency points of SS are simple. Let C1C_1 be the conic with the maximal number mm of lines tangent to it. In the simplified presentation of π1(CP2S)\boldsymbol{\pi_1(\mathbb{C}\mathbb{P}^2-S)}, let aa denote the generator corresponding to C1C_1.

Simplified presentation conjecture. The presentation has the following properties:

  1. It has mm relations of the form
(axi)2=(xia)2,(a x_i)^2=(x_i a)^2,

where the xix_i are some generators of the group. 2. For any two generators yy and zz different from aa, one has

yaza1=aza1y.y a z a^{-1}=a z a^{-1}y.

In some computed presentations, relations of the second type may simplify to commutative relations between generators as a consequence of the other relations; the conjecture concerns the resulting simplified presentation and remains unverified in general.

Sources & referencesView supporting material

Primary source

Meirav Amram, David Garber and Mina Teicher, “Fundamental groups of Tangent Conic-Line arrangements with Singularities up to order 6”, arXiv:math/0305418 (2006).

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