2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/60926We prove L^p estimates for the "biest", a trilinear multiplier with singular symbol which arises naturally in the expansion of eigenfunctions of a Schrodinger operator, and which is also related to the bilinear Hilbert transform. In a previous paper these estimates were obtained for a simpler Walsh model for this operator, but in the Fourier case additional complications arise due to the inability to perfectly localize in both space and frequency.30 pages, no figures, submitted, Math. AnnalenClassical Analysis and ODEs42B15text