A Critique and Improvement of an Evaluation Metric for Text Segmentation Lev Pevzner author Marti A Hearst author 2002 text journal article Computational Linguistics continuing MIT Press Cambridge, MA periodical academic journal pevzner-hearst-2002-critique 10.1162/089120102317341756 https://aclanthology.org/J02-1002/ 2002 28 1 19 36