‘Enhancing’ Hypotactic Verbal Group Complexes: Causative

Halliday & Matthiessen (2004: 509):

Such complexes are involved in the realisation of the transitivity system of agency. … We can always express this agency analytically, by saying John made the ball roll, where made … roll is a hypotactic verbal group complex.  Here, the causative verbal group complex is an alternative realisation of the feature of ‘effective’ agency: an additional participant is introduced into the clause through the expansion of the verbal group realising the Process.