Stability of Weighted Norm Inequalities

We show that while individual Riesz transforms are two weight norm stable under biLipschitz change of variables on $A_{\infty}$ weights, they are two weight norm unstable under even rotational change of variables on doubling weights. More precisely, we show that individual Riesz transforms are unstable under a set of rotations having full measure, which includes rotations arbitrarily close to the identity. This provides an operator theoretic distinction between $A_{\infty}$ weights and doubling weights. More generally, all iterated Riesz transforms of odd order are rotationally unstable on pairs of doubling weights, thus demonstrating the need for characterizations of iterated Riesz transform inequalities using testing conditions for doubling measures, as opposed to the typically stable 'bump' conditions.
Comment: 43 pages, followed by 8 pages of appendices and references. Several proofs are corrected, including circumventing an error found in a previous version of the T1 theorem of[AlSaUr]. Futhermore, an additional subsection is added to the appendix relating stability and sparse operators. Main results unchanged. To appear in Revista Matem\'atica Iberoamericana