@Misc{ BucGiaTre17, author = { Bucur, Dorin and Giacomini, Alessandro and Trebeschi, Paola }, title = { Best constant in Poincaré inequalities with traces: a free discontinuity approach }, journal = { }, year = { 2017 }, pages = { }, URL = { http://cvgmt.sns.it/paper/3502/ }, note = { cvgmt preprint} }