Over the last two decades, there has been extensive study targeting unsupervised constituency parsing (Klein and Manning, 2002, 2004, 2005Bod, 2006a,b;Ponvert et al., 2011) and dependency parsing (Klein and Manning, 2004;Smith and Eisner, 2006;Spitkovsky et al., 2010;Han et al., 2017).
all of these approaches are based on linguistic annotations.