The Weak Sequential Closure of Certain Sets of Extreme Points in a Von Neumann Algebra J. ConwayJ. Szucs Indiana University Mathematics Journal 1973 text pdf 10.1512/iumj.1973.22.22061 10.1512/iumj.1973.22.22061 en Indiana Univ. Math. J. 22 (1973) 763 - 768 state-of-the-art mathematics http://iumj.org/access/