As in experiment #3 ( §4.1), we modified the base system in exactly one way: we swapped out gold part-of-speech tags and replaced them with a flat distributional similarity clustering.
to simpler models, which suffer multi-point drops in accuracy from switching to unsupervised tags (e.g., 2.6%), our new system's performance degrades only slightly, by 0.2% (see Tables 4 and 5).