Best Constants in Sobolev Inequalities for Functions Vanishing on Some Part of the Boundary and Related Questions P. LionsF. PacellaM. Tricarico Indiana University Mathematics Journal 1988 text pdf 10.1512/iumj.1988.37.37015 10.1512/iumj.1988.37.37015 en Indiana Univ. Math. J. 37 (1988) 301 - 324 state-of-the-art mathematics http://iumj.org/access/