We characterize all the extreme points of the unit ball in the space of trilinear forms on the Hilbert space . This answers a question posed by R. Grząślewicz and K. John [7], who solved the corresponding problem for the real Hilbert space . As an application we determine the best constant in the inequality between the Hilbert-Schmidt norm and the norm of trilinear forms.
@article{bwmeta1.element.bwnjournal-article-smv138i1p81bwm, author = {Fernando Cobos and Thomas K\"uhn and Jaak Peetre}, title = {Extreme points of the complex binary trilinear ball}, journal = {Studia Mathematica}, volume = {141}, year = {2000}, pages = {81-92}, zbl = {0956.46013}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-smv138i1p81bwm} }
Cobos, Fernando; Kühn, Thomas; Peetre, Jaak. Extreme points of the complex binary trilinear ball. Studia Mathematica, Tome 141 (2000) pp. 81-92. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-smv138i1p81bwm/
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