The Closure of the (U + K)-Orbit of Shift-Like Operators L. Marcoux Indiana University Mathematics Journal 1992 text pdf 10.1512/iumj.1992.41.41059 10.1512/iumj.1992.41.41059 en Indiana Univ. Math. J. 41 (1992) 1211 - 1223 state-of-the-art mathematics http://iumj.org/access/