Inversion, Part 2

$\langle$displ-const$\rangle$:
Possible values: [set1: +], [set1: -]
In the previous section, we saw how inversion is triggered using the $\langle$invlink$\rangle$, $\langle$inv$\rangle$, $\langle$wh$\rangle$ features. Inversion involves movement of the verb from V to C. This movement process is represented using the $\langle$displ-const$\rangle$ feature which is used to simulate Multi-Component TAGs.^28.1 The sub-value set1 indicates the inversion multi-component set; while there are not currently any other uses of this mechanism, it could be expanded with other sets receiving different set values. The $\langle$displ-const$\rangle$ feature is used to ensure adjunction of two trees, which in this case are the auxiliary tree corresponding to the moved verb (S adjunct) and the auxiliary tree corresponding to the trace of the moved verb (VP adjunct). The following equations are used:

(524)0(524

(525)

S_r.b:$\langle$displ-const set1 $\rangle = -$   (525)0(525

(526)

S.t:$\langle$displ-const set1 $\rangle = +$   (526)0(526

(527)

VP.b:$\langle$displ-const set1$\rangle =$ V.t:$\langle$displ-const set1$\rangle$   (527)0(527

(528)

V.b:$\langle$displ-const set1 $\rangle = +$   (528)0(528

(529)

S_r.b:$\langle$displ-const set1$\rangle =$ VP.t:$\langle$displ-const set1$\rangle$