Cobos, FernandoKühn, ThomasPeetre, Jaak2023-06-202023-06-2020000039-3223https://hdl.handle.net/20.500.14352/57309We characterize all the extreme points of the unit ball in the space of trilinear forms on the Hilbert space C-2. This answers a question posed by R. Grzaslewicz and K. John [7], who solved the corresponding problem for the real Hilbert space R-2. As an application we determine the best constant in the inequality between the Hilbert-Schmidt norm and the norm of trilinear forms.engjournal articlehttp://www.impan.pl/restricted access517.98Trilinear formnormHilbert-Schmidt normextreme pointextreme point of unit ballAnálisis funcional y teoría de operadores