Parser with head movement and covert movement

[IanTayler]

Both are mentioned in Torr and Stabler (2016) but were actually some of the first extensions mentioned by Stabler in his early work on MGs.

Both are salient. Covert movement was an important part of Chomsky's (1995) model, and head movement is ubiquitous. While Chomsky assumed head movement happened at PF and could be ignored by syntacticians, what happens at PF crucially cannot be ignored by anyone implementing a parser.