Let (, d, ) be a metric measure space of homogeneous type in the sense of Coifman and Weiss. In this article, the authors prove that bilinear operators, which are finite combinations of compositions of commutators and Calderón-Zygmund operators, are bounded from H 1 ()×BMO() to L 1 (). The authors also prove that the commutator, generated by any b ∈ BMO() and Calderón-Zygmund operator, is bounded from the Hardy-type spacethat ensures the boundedness of the commutators from to L 1 (). The novelties appearing in these approaches exist in applications of the multiresolution analysis of the wavelets on metric measure spaces of homogeneous type, the bilinear decomposition of the product space H 1 () × BMO(), the (sub)bilinear decomposition of commutators, the proof of off-diagonal estimates of the action of Calderón-Zygmund operators on the wavelet functions, and the boundedness of the almost diagonal matrix on the spaces H 1 () and BMO(). Notably, throughout this article, is not assumed to satisfy the reverse doubling condition.
KEYWORDSbilinear decomposition, BMO space, Calderón-Zygmund operator, commutator, Hardy space, space of homogeneous type, wavelet for the theory of singular integrals and function spaces. A metric space (, d) is a set equipped with a metric d such that, for any x, , z ∈ , (i) d(x, y) = d(y, x);