What is a good way of summarizing why lexical threading is needed? In Bouma et al., I think its role is to eliminate subject/complement extraction rules. But in the Grammar Matrix we still use subject and complement extraction. I am assuming we still get some streamlining out of it, but I cannot quite put my finger on it.
Related to this, what’s a good way of explaining the type gap: its local features are the sole item on its SLASH list; what’s a good way of summarizing how this later fits into the mechanics of extraction?