TY - JOUR
T1 - On the interpolation constants for variable Lebesgue spaces
AU - Karlovych, Oleksiy
AU - Shargorodsky, Eugene
N1 - Funding Information:
This work was supported by national funds through the FCT—Fundação para a Ciência e a Tecnologia, I.P. (Portuguese Foundation for Science and Technology) within the scope of the project UIDB/00297/2020 (Centro de Matemática e Aplicações).
Publisher Copyright:
© 2023 Wiley-VCH GmbH.
PY - 2023/7/7
Y1 - 2023/7/7
N2 - For (Figure presented.) and variable exponents (Figure presented.) and (Figure presented.) with values in [1, ∞], let the variable exponents (Figure presented.) be defined by (Figure presented.) The Riesz–Thorin–type interpolation theorem for variable Lebesgue spaces says that if a linear operator T acts boundedly from the variable Lebesgue space (Figure presented.) to the variable Lebesgue space (Figure presented.) for (Figure presented.), then (Figure presented.) where C is an interpolation constant independent of T. We consider two different modulars (Figure presented.) and (Figure presented.) generating variable Lebesgue spaces and give upper estimates for the corresponding interpolation constants C
max and C
sum, which imply that (Figure presented.) and (Figure presented.), as well as, lead to sufficient conditions for (Figure presented.) and (Figure presented.). We also construct an example showing that, in many cases, our upper estimates are sharp and the interpolation constant is greater than one, even if one requires that (Figure presented.), (Figure presented.) are Lipschitz continuous and bounded away from one and infinity (in this case, (Figure presented.)).
AB - For (Figure presented.) and variable exponents (Figure presented.) and (Figure presented.) with values in [1, ∞], let the variable exponents (Figure presented.) be defined by (Figure presented.) The Riesz–Thorin–type interpolation theorem for variable Lebesgue spaces says that if a linear operator T acts boundedly from the variable Lebesgue space (Figure presented.) to the variable Lebesgue space (Figure presented.) for (Figure presented.), then (Figure presented.) where C is an interpolation constant independent of T. We consider two different modulars (Figure presented.) and (Figure presented.) generating variable Lebesgue spaces and give upper estimates for the corresponding interpolation constants C
max and C
sum, which imply that (Figure presented.) and (Figure presented.), as well as, lead to sufficient conditions for (Figure presented.) and (Figure presented.). We also construct an example showing that, in many cases, our upper estimates are sharp and the interpolation constant is greater than one, even if one requires that (Figure presented.), (Figure presented.) are Lipschitz continuous and bounded away from one and infinity (in this case, (Figure presented.)).
KW - Calderón product
KW - complex method of interpolation
KW - interpolation constant
KW - Riesz–Thorin interpolation theorem
KW - variable Lebesgue space
UR - http://www.scopus.com/inward/record.url?scp=85152251816&partnerID=8YFLogxK
U2 - 10.1002/mana.202100549
DO - 10.1002/mana.202100549
M3 - Article
AN - SCOPUS:85152251816
SN - 1522-2616
VL - 296
SP - 2877
EP - 2902
JO - Mathematische Nachrichten
JF - Mathematische Nachrichten
IS - 7
ER -