Multilinear Marcinkiewicz integral extrapolation conjecture

Let Ω\Omega be a function on (Rn)m({\mathbb R}^n)^m satisfying conditions (i), (ii), and (iii) in the definition of a multilinear Marcinkiewicz integral. For Schwartz functions f=(f1,,fm)\vec f=(f_1,\ldots,f_m), define

Ft(f)(x)=1tm(B(0,t))mΩ(y)i=1myin1i=1mfi(xyi)dy,F_t(\vec f)(x)=\frac{1}{t^m}\int_{(B(0,t))^m}\frac{\Omega(\vec y)}{\prod_{i=1}^m|y_i|^{n-1}}\prod_{i=1}^m f_i(x-y_i)\,d\vec y,

and

μ(f)(x)=(0Ft(f)(x)2dtt)1/2.\mu(\vec f)(x)=\left(\int_0^\infty|F_t(\vec f)(x)|^2\,\frac{dt}{t}\right)^{1/2}.

Multilinear Marcinkiewicz integral extrapolation conjecture. If μ\mu is bounded from Lq1(Rn)××Lqm(Rn)L^{q_1}({\mathbb R}^n)\times\cdots\times L^{q_m}({\mathbb R}^n) to Lq(Rn)L^q({\mathbb R}^n) for some 1<q1,,qm<1<q_1,\ldots,q_m<\infty satisfying 1/q=1/q1++1/qm1/q=1/q_1+\cdots+1/q_m, then μ\mu is bounded from Lp1(Rn)××Lpm(Rn)L^{p_1}({\mathbb R}^n)\times\cdots\times L^{p_m}({\mathbb R}^n) to Lp(Rn)L^p({\mathbb R}^n) for every 1<p1,,pm<1<p_1,\ldots,p_m<\infty satisfying 1/p=1/p1++1/pm1/p=1/p_1+\cdots+1/p_m. This conjectures that boundedness at one admissible tuple of exponents implies boundedness at every admissible tuple, under the stated kernel conditions.

Sources & referencesView supporting material

Primary source

Qingying Xue and Kozo Yabuta, “The existence and boundedness of multilinear Marcinkiewicz integrals on Companato spaces”, arXiv:1512.00663 (2015).

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