The main goal of this paper is to provide a complete description of the space of pointwise multipliers M(XF, XG) between two Calderón–Lozanovski˘ı spaces XF and XG.
The key results are:
M(XF, XG) = XG⊖F if, and only if, the triple (X, F, G) is "nice", meaning that the fundamental function ψX of the rearrangement invariant space X does not vanish at zero, the Young function F is finite, and the Young function G jumps to infinity.
If the triple (X, F, G) fails to be nice, then M(XF, XG) = XG⊖1F, where G⊖1F is a truncated version of the generalized Young conjugate G⊖F.
The authors also provide a complete picture on the factorization of Calderón–Lozanovski˘ı spaces, showing that XF ⊙M(XF, XG) = XG if, and only if, F −1(G⊖F)−1 ≈ G−1.
The proofs rely heavily on the machinery of generalized Young conjugate functions, which extends the classical Köthe duality theory of Orlicz spaces. The results hold for rearrangement invariant spaces defined on both I = [0, 1] and I = [0, ∞), without any separability assumptions.
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by Tomasz Kiwer... о arxiv.org 10-03-2024
https://arxiv.org/pdf/2410.01420.pdfГлибші Запити