Sjef Barbiers is Professor of Dutch Linguistics at Leiden University. He was the leader of the Syntactic Atlas of the Dutch Dialects and European Dialect Syntax projects. He is currently the Scientific Director of the Leiden University Centre for Linguistics. Norbert Corver is Professor of Dutch Linguistics at Utrecht University. He is co-editor of several books, including Semi-lexical Categories (with van Riemsdijk, 2001, De Gruyter Mouton) and Diagnosing Syntax (with Cheng, 2013, OUP) He is currently the scientific director of Utrecht University Institute for Language Sciences. Maria Polinsky is Professor of Linguistics at the University of Maryland and Director of the National Heritage Research Center at UCLA. She has served on the editorial boards of multiple journals and advisory boards of several international centres. She is the author of multiple scholarly articles and several books, and editor of several handbooks.