Characteristic Varieties for a Class of Line Arrangements

摘要

Let A be a line arrangement in the complex projective plane P~2, having the points of multi- plicity ≥ 3 situated on two lines in A, say H_0 and H_∞. Then we show that the non-local irreducible components of the first resonance varietyR_1(A) are 2-dimensional and correspond to parallelograms Pin C~2 = P~2 H_∞ whose sides are inAand for which H_0 is a diagonal.