Iterated commutators under a joint condition on the tuple of multiplying functions

Tuomas Hytönen, Kangwei Li, Tuomas Oikari

We present a pair of joint conditions on the two functions $b_1,b_2$ strictly weaker than $b_1,b_2\in \mathrm{BMO}$ that almost characterize the $L^2$ boundedness of the iter…