We explore the connection between p-regular operators on Banach function spaces and weighted p-estimates. In particular, our results focus on the following problem. Given finite measure spaces µ and ν, let T be an operator defined from a Banach function space X(ν) and taking values on L p (vdµ) for v in certain family of weights V ⊂ L 1 (µ) + : we analyze the existence of a bounded family of weights W ⊂ L 1 (ν) + such that for every v ∈ V there is w ∈ W in such a way that T : L p (wdν) → L p (vdµ) is continuous uniformly on V . A condition for the existence of such a family is given in terms of p-regularity of the integration map associated to a certain vector measure induced by the operator T .2010 Mathematics Subject Classification. 46E30,46B42,47B10. Key words and phrases. Banach function space; p-regular operator; weighted p-estimate. E. A. Sánchez Pérez gratefully acknowledges support of Spanish Ministerio de Economía, Industria y Competitividad through grant MTM2016-77054-C2-1-P. P. Tradacete gratefully acknowledges support of Spanish Ministerio de Economía, Industria y Competitividad through grants MTM2016-76808-P and MTM2016-75196-P.
PreliminariesLet (Ω, Σ, µ) be a finite measure space. Let L 0 (µ) be the space of all measurable real functions on Ω, identifying functions that are equal µ-a.e. We say that a Banach function space over µ is a Banach space X(µ) ⊆ L 0 (µ) that contains all simple functions, and whenever |f | ≤ |g| and g ∈ X(µ), then f ∈ X(µ) with f X(µ) ≤ g X(µ) . For the aim of simplicity, we will write sometimes X instead of X(µ) if the measure does not play a relevant role or is clear in the context. Recall X(µ) is order continuous if for every sequence (f n ) n ∈ X(µ), f n ↓ 0 implies f n X(µ) → 0. In this case, the Köthe dual X(µ) ′ = {g ∈ L 0 (µ) : f g ∈ L 1 (µ) whenever f ∈ X(µ)}, p-REGULAR OPERATORS AND WEIGHTS