In syntax, shifting occurs when two or more constituents appearing on the same side of their common head exchange positions in a sense to obtain non-canonical order.
The theoretical analysis of shifting varies in part depending on the theory of sentence structure that one adopts.
It can also occur, for instance, in NPs: These examples again illustrate shifting that is motivated by the relative weight of the constituents involved.
Since the finite verb is viewed as the head of the clause in each case, these data allow an analysis in terms of shifting.
Regardless of whether one chooses the constituency- or the dependency-based analysis, the important thing about these examples is the relative flatness of the structure.
This flatness results in a situation where shifting does not necessitate a discontinuity (i.e. no long distance dependency), for there can be no crossing lines in the trees.
The following trees further illustrate the point: Again due to the flatness of structure, shifting does not result in a discontinuity.
[6] Jackendoff and Culicover argue for an analysis like that shown with the flatter trees above, whereby heavy NP shift does not result from movement, but rather from a degree of optionality in the ordering of a verb's complements.
Their analysis in terms of a strictly binary branching tree resulting from leftward movements would in turn be able to explain this restriction.