a strategy for the expression of the necessarily shared participant in the relative clause of an externally headed - relative clause construction, in which the participant is not expressed at all in the relative clause. Example: I ate the cheesecake [that Carol baked] uses the gap strategy because the shared participant, the cheesecake, is expressed only as the external relative clause head, and not at all in the relative clause that Carol baked. (Section 19.2.2)