@MISC{Zetzsche2018a,
	AUTHOR		= {Zetzsche, Georg},
	TITLE		= {PTL-separability and closures for WQOs on words},
	YEAR		= {2018},
	NOTE		= {To appear in Proc. of the Thirty-Third Annual ACM/IEEE Symposium on Logic in Computer Science (LICS 2018)}
}