Phase transitions on the Toeplitz algebras of Baumslag-Solitar semigroups Astrid an HuefLisa ClarkIain Raeburn Indiana University Mathematics Journal 2016 text pdf 10.1512/iumj.2016.65.5934 10.1512/iumj.2016.65.5934 en Indiana Univ. Math. J. 65 (2016) 2137 - 2173 state-of-the-art mathematics http://iumj.org/access/