Editing Minimalist program (section)

=== Phase edge ===
Chomsky theorized that syntactic operations must obey the phase impenetrability condition (PIC) which essentially requires that movement be from the left-edge of a phase. The PIC has been variously formulated in the literature. The [[extended projection principle]] feature that is on the heads of phases triggers the intermediate movement steps to phase edges.<ref name=":0" />

====Phase impenetrability condition (PIC)====

Movement of a constituent out of a phase is (in the general case) only permitted if the constituent has first moved to the left edge of the phase (XP).

The edge of a head X is defined as the residue outside of X', in either specifier of X and adjuncts to XP.<ref>{{Cite book|last=Chomsky|first=Noam|url=https://books.google.com/books?id=E-IbAQAAIAAJ|title=Derivation by Phase|date=1999|publisher=MIT, Department of Linguistics|language=en}}</ref>

English successive cyclic wh-movement obeys the PIC.<ref name=":0" /> Sentence (7) has two phases: ''v''P and CP. Relative to the application of movement, ''who'' moves from the (lower) ''v''P phase to the (higher) CP phase in two steps:

*Step 1: '''''who''''' moves from the complement position of VP to the left edge of ''v''P, and the EPP feature of the verb forces movement of '''''who''''' to the edge of vP.
* Step 2: '''''who'''''  moves from the left edge of the lower ''v''P phase to the specifier of the (higher) CP phase.

 (7)  [<sub>CP</sub> '''''Who''' did you'' [<sub>vP</sub> ''see'' <s>who</s>]]?

 {| class="wikitable"
 |<!--col1-->[[File:Phasal_Movement_Syntax_tree-_step_1.png|300x300px]]
 |<!--col2-->[[File:Phasal_movement_tree-_step_1.png|300x300px]]
 |-
 |<!--col1-->Step 1: wh-phrase moves to edge of vP phase
 |<!--col2-->Step 2: wh-phrase moves to edge of CP phase
 |}

====Medumba wh-movement====
Another example of PIC can be observed when analyzing A'-agreement in [[Medumba language|Medumba]]. A'-agreement is a term used for the morphological reflex of A'-movement of an XP.<ref name=":5" /> In Medumba, when the moved phrase reaches a phase edge, a high low tonal melody is added to the head of the complement of the phase head. Since A'-agreement in Medumba requires movement, the presence of agreement on the complements of phase heads shows that the wh-word  moves to the edges of phases and obeys PIC.<ref name=":5">{{Cite thesis|last=Keupdjio|first=H. S.|date=2020|title=The syntax of A' -dependencies in Bamileke Medumba (T).|url=https://open.library.ubc.ca/collections/ubctheses/24/items/1.0389713|journal=University of British Columbia|doi=10.14288/1.0389713}}</ref>

Example:<ref name=":5" />

The sentence (2a) has a high low tone on the verb '''''nɔ́ʔ''''' and tense '''''ʤʉ̀n''''', therefore is grammatical.

(2a) [<sub>CP</sub> á wʉ́ Wàtɛ̀t '''nɔ́ɔ̀ʔ''' [<sub>vP</sub> '''ⁿ-ʤʉ́ʉ̀n''' á?]]

'Who did Watat see?'

The sentence (2b) does not have a high low tone on the verb '''''nɔ́ʔ''''' and tense '''''ʤʉ̀n''''', therefore is not grammatical.

(2b) *[<sub>CP</sub> á wʉ́ Wàtɛ̀t '''nɔ́ʔ''' [<sub>vP</sub> '''ⁿ-ʤʉ́n''' á?]]

<nowiki>*</nowiki>'Who did Watat see?'

To generate the grammatical sentence (2a), the ''wh''-phrase ''á wʉ́'' moves from the vP phase to the CP phase. To obey PIC, this movement must take two steps since the wh-phrase needs to move to the edge of the vP phase in order to move out of the lower phase.

* Step 1: First, the ''wh''-phrase moves from the complement of VP to the edge of the vP phase to avoid violating PIC. In this position, the agreement is expressed on the verb ''ʤʉ̀n'' and surfaces as a high low (HL) tone melody (''ⁿ-ʤʉ́ʉ̀n''). The agreement is expressed on the verb which is the head of the complement of the v phase head.
[[File:Syntax_tree_wh-movement_in_Medumba.png|none|thumb|297x297px|Step 1: wh-phrase moves to edge of vP]]
* Step 2: Now that it is at the edge of the vP phase, the ''wh''-phrase is able to leave the vP phase and move to the Spec-C position of the CP phase. Agreement is expressed on the tense ''nɔ́ʔ'' as a high low tone melody (nɔ́ɔ̀ʔ). The tense which agreement is expressed on is the head of the complement of the C phase head
[[File:Syntax_tree_Wh-movement_in_Medumba_(part_2).png|none|thumb|293x293px|Step 2: wh-phrase moves from vP phase to CP phase]]

One can confirm that A' agreement only occurs with movement by examining sentences where the wh-phrase does not move. In sentence (2c) below, one can observe that there is no high low tone melody on the verb '''''nɔ́ʔ''''' and tense '''''fá''''' since the wh-word does not move to the edge of the vP and CP phase.<ref name=":5" />

(2c) [m-ɛ́n '''nɔ́ʔ''' '''fá''' bɔ̀ á wʉ́ á]

'The child gave the bag to who?'