Homotopy types of line arrangements (Q1210506)

We prove that the complement of the real affine line arrangement in \(\mathbb{C}^ 2\) is homotopy equivalent to the canonical 2-complex associated with Randell's presentation of the fundamental group. This provides a much smaller model for the homotopy type of the complement of a real affine 2- or central 3-arrangement than the Salvetti complex and its cousins. As an application we prove that there exist (infinitely many) pairs of central arrangements in \(\mathbb{C}^ 3\) with different underlying matroids whose complements are homotopy equivalent. We also show that two real 3-arrangements whose oriented matroids are connected by a sequence of flips are homotopy equivalent.