2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/144268In this article we prove that the $n$-linear operator whose symbol is the characteristic function of the simplex $Δ_n = ξ_1 < ... < ξ_n$ is bounded from $L^2 \times ... \times L^2$ into $L^{2/n}$, generalizing in this way our previous work on the "bi-est" operator (which corresponds to the case $n=3$) as well as Lacey-Thiele theorem on the bi-linear Hilbert transform (which corresponds to the case $n=2$).52 pages, 6 figuresClassical Analysis and ODEs42B15text