636 research outputs found
Summability of multilinear forms on classical sequence spaces
We present an extension of the Hardy--Littlewood inequality for multilinear
forms. More precisely, let be the real or complex scalar field and
be positive integers with and be
positive integers such that .
() If then there is a
constant (not depending on ) such that
\left( \sum_{i_{1},\dots ,i_{k}=1}^{n}\left| T\left( e_{i_{1}}^{n_{1}},\dots
,e_{i_{k}}^{n_{k}}\right) \right| ^{r}\right) ^{% \frac{1}{r}}\leq
D_{m,r,p,k}^{\mathbb{K}} \cdot n^{max\left\{ \frac{%
2kp-kpr-pr+2rm}{2pr},0\right\} }\left| T\right| for all -linear forms
and all
positive integers . Moreover, the exponent is optimal.
() If then there is a constant (not depending on ) such that \left(
\sum_{i_{1},\dots ,i_{k}=1}^{n }\left| T\left( e_{i_{1}}^{n_{1}},\dots
,e_{i_{k}}^{n_{k}}\right) \right| ^{r }\right) ^{% \frac{1}{r }}\leq D_{m,r,p,
k}^{\mathbb{K}} \cdot n^{ max \left\{\frac{% p-rp+rm}{pr}, 0\right\}}\left|
T\right| for all -linear forms and all positive integers . Moreover,
the exponent is optimal.
The case recovers a recent result due to G. Araujo and D. Pellegrino
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