C. P. BoyerDepartment of Mathematics and Statistics, University of New MexicoB. M. MannDepartment of Mathematics and Statistics, University of New MexicoJ. C. HurtubiseDepartment of Mathematics, McGill UniversityR. J. MilgramDepartment of Mathematics and Statistics, University of New Mexico
A Sobolev space in several variables in an$L$^{1}-type norm is not complemented in its second dual. Hence it is not isomorphic as a Banach space to any complemented subspace of a Banach lattice.