Signed graphs and the freeness of the Weyl subarrangements of type $B_{\ell }$

Daisuke Suyama, Michele Torielli, Shuhei Tsujie

A Weyl arrangement is the hyperplane arrangement defined by a root system. Arnold and Saito proved that every Weyl arrangement is free. The Weyl subarrangements of type $A_{\ell }$…