A Dynamic Antisymmetry Approach to pro-drop in Persian

In the present study two significant characteristics of pro-drop languages, i.e. the absence of lexical subject and subject-verb free inversion will be investigated in light of Dynamic Anti-Symmetry (hence, DAS) framework (Moro, 2000) in Persian:
[pro ketab ra peyda kardam]
pro book OM found
[Qaza xord Arash]
ate Arash
These two characteristics are assumed to be the byproduct of the point of symmetry and the attempt to break this symmetry. According to DAS, we took movement as a symmetry breaking process and not a process through which uninterpretable features can be checked. By extending Merge operation, Moro (2004) argues that it is possible to have an unspecified structure in which none of the element participated in merge can be projected. He calls this unspecified structure bare small clause. Bare small clause is a kind of clause which is the complement of copulas and by virtue of having no position for functional heads; it can include a point of symmetry. Thid small cluse is the product of merging of two maximal projections none of which is projected in the resulting structure. By definition, this small clause is nothing more than a point of symmetry which must be broken in line with linear correspondent axiom (hence, LCA) (kanye, 1994). Accordingly, any merger of DP and VP leads to a point of symmetry; provided that, that DP plays the role of the subject of the whole phrase. This point of symmetry will be broken at PF in line with LCA.
According to Cardinaletti & Starke (1999), Holmberg (2005) & Roberts (2007) pro is no longer a null category but a weak pronoun. This assumption is accepted through the current article. Therefore, Pro is assumed to be a weak pronoun and hence a DP which undergoes deletion at PF after being merged with VP and constructing a point of symmetry. It should be mentioned that in this article it is accepted that either moving or deleting of one of the symmetry makers can break the point of symmetry. This justifies the absence of lexical subject.
Spec,vP and Spec,VP are suggested to be the main position for subject in transitive/ unergative and unaccusative structures respectively, according to UTAH. In all of these positions a point of symmetry is observed which can be broken in two ways: by verb movement or by subject movement; this justifies subject-verb free inversion in pro-drop languages. The landing site for pre-verbal subject is assumed to be Spec,TP and Spec,FocP in case the subject gets stress. The landing site for post-verbal subject in unaccusative structures is little v and in transitive/unergative structures is head T.
In conclusion, we can say that in this study by assuming pro as a weak pronoun and hence a DP, we showed that omitting subject in a pro-drop language is a byproduct of observing LCA at PF. Meanwhile, we argued that in Persian according to UTAH, the main position for subject in sentences with transitive/ unergative predicators is Spec,vP and in sentences with unaccusative predicators is Spec,VP. All of these positions bear the point of symmetry which can be broken in two ways: by movement of either the verb or the subject. These ways of breaking points of symmetry can justify the subject-verb free inversion in pro-drop languages.