Logarithmic bundles of deformed Weyl arrangements of type $A_2$
Résumé
We consider generalized deformations of the Weyl arrangement of type $A_2$, which include the extended Shi and Catalan arrangements, well-known to be free. We study all the other cases, and show that they are Steiner bundles. Also, we determine explicitly their unstable lines. As a corollary, some counter-examples to the shift isomorphism problem are given.
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