This thesis investigates a set of clause-initial discourse particles in North Hail Arabic (NHA), a dialect spoken in Saudi Arabia. The particles are shown to be heads in the C-domain with topic-marking function. It is shown that the topics typology put forward by Frascarelli and Hinterhölzl (2007) for German and Italian extends to NHA. The Shifting Topic (S-Topic) is situated above the Focus Phrase, followed by Contrastive Topic (C-Topic), which is in turn followed by Familiar Topic (F-Topic). S-Topic can be marked by either C-particles mar or ʕad.
The particles tara and ʔaktɪn mark an entity expressing C-Topic, while the particle ʁedɪ, tsin, ʔeʃwa and tigil mark an entity expressing F-Topic. All particles are argued to carry a valued [TOP] feature. However, they are different with respect to whether they have φ-content. This difference motivates the distinction between agreeing particles (having φ-content) and nonagreeing particles (not having φ-content). The study shows that the agreeing particles are probes, being with unvalued φ-features, establishing an Agree relation (Chomsky 2000, 2001) with the element that carries a matching unvalued [TOP] feature and valued φ-features. This results in the valuation of the unvalued φ-features of the agreeing particle, and the valuation of the matching unvalued [TOP] feature of the goal. As a result, the topic interpretation is achieved via the chain created by the head of the topic and the topicalized item. The study shows that when the goal has φ-content, an inflectional suffix expressing the same φ-content as that of the goal is suffixed to the particle.
The motivation behind counting the [TOP] feature on the goal to be unvalued comes from the cases where the goal is the object. NHA data show that the object moves to a position where it gets accessible to the probe, the agreeing particle, following Chomsky (2000, 2001), Bošković (2007, 2014) and Holmberg et al. (2017). This is consistent in the case with multiple topics, where the two topics, the subject and the object, tuck in the projecting headed by the particle (Richards 1997, 1999).
As for the non-agreeing particles, the study argues that, instead of φ-content, these heads are endowed with an [EPP] feature, which attracts the element carrying the matching unvalued [TOP] feature to the Spec position of the relevant head. This accounts for why such particles cannot be clause-initial. These facts motivate the assumption that movement to the left periphery (i.e. topicalization) is forced when the head of the Topic Phrase is not endowed with any φ-content.