Algebraic isomorphisms and spectra of triangular limit algebras Allan DonsigDavid PittsS. Power 47L4047L50limit algebrasspectraalgebraic isomorphisms Indiana University Mathematics Journal 2001 text pdf 10.1512/iumj.2001.50.2113 10.1512/iumj.2001.50.2113 en Indiana Univ. Math. J. 50 (2001) 1131 - 1148 state-of-the-art mathematics http://iumj.org/access/