Yulia Dubov Michael Kaminski The Power of Non-deterministic Reassignment in Infinite-Alphabet Pushdown Automata. 107-127 2009 Languages: From Formal to Natural http://dx.doi.org/10.1007/978-3-642-01748-3_8 conf/birthday/2009francez db/conf/birthday/francez2009.html#DubovK09