Triangularizing Semigroups of Compact Operators Eric NordgrenHeydar RadjaviPeter Rosenthal Indiana University Mathematics Journal 1984 text pdf 10.1512/iumj.1984.33.33014 10.1512/iumj.1984.33.33014 en Indiana Univ. Math. J. 33 (1984) 271 - 275 state-of-the-art mathematics http://iumj.org/access/