Area-minimizing cones over the canonical imbedding of symmetric $R$-spaces Takahiro Kanno 49Q05area-minimizing surfaceconesymmetric space Indiana University Mathematics Journal 2002 text pdf 10.1512/iumj.2002.51.2141 10.1512/iumj.2002.51.2141 en Indiana Univ. Math. J. 51 (2002) 89 - 126 state-of-the-art mathematics http://iumj.org/access/