This dissertation would not have been possible without the prodigious, incomparable, heuristic and great help of my supervisor, Professor Titular. Ignasi Navarro i Ferrando, who stood close to me every step, whenever I needed, and provided everything necessary for the progress of my thesis. Many thanks go, too, to Renata Geld, Head of the English Department at the Faculty of Foreign Languages, Zagreb, Croatia, who, very conventionally conduced promising facilities during my Research Stay, there. Certainly, there's also a place here to thank the head of the English Department and many of my colleagues at the Faculty of Foreign Languages, Tirana, Albania, who willingly shared with me very useful scientific knowledge throughout the days while at work. I would also like to thank the representatives of the University departments of Jaume I, who were always ready in fulfilling and replying many of my queries while working on my dissertation. Last but not least, as the saying goes after Shakespeare, I would like to thank my father and especially my mother who, although resting in peace, were a strong encouragement and along with my two most loving daughters Estrea and Nejmia renewed and shaped my previous and actual scientific information in the field of linguistics by giving me peace, love and tenderness. On the whole, I would like to thank everyone who in a way or another finds this work useful and serves them hereafter.

A preposition is a word or set of words that indicates location or some other relationship between a noun or pronoun and other parts of the sentence. It refers to the word or phrase which shows the relationship between one thing and another, linking nouns, pronouns and phrases to other words in a sentence. They are abstract words that have no concrete meaning. They merely show the relationships between groups of words. Within a preposition, there are many different variations in meaning that are conveyed. The proper interpretation of prepositions is an important issue for automatic natural language understanding. Although the complexity of preposition usage has been argued for and documented by various scholars in linguistics, psycholinguistics, and computational linguistics, very few studies have been done on the function of prepositions in natural language processing (NLP) applications. The reason is that prepositions are probably the most polysemous category and thus, their linguistic realizations are difficult to predict and their cross-linguistic regularities difficult to identify. Prepositions play a major role in the syntactic structures of the English language and they often make an essential contribution to sentence meaning by signifying temporal and spatial relationships, as well as abstract relations involving cause and purpose, agent and instrument, manner and accompaniment, support and much more. They are sensitive linguistic elements that are culturally acceptable and very well known to all members of the same linguistic community. According to cognitive semantics, the figurative senses of a preposition are extended from its spatial senses through conceptual metaphors. In a pedagogical context, it may be useful to draw learners' attention to those aspects of a preposition's spatial sense that are especially relevant for its metaphorization processes. Prepositions have type restrictions on their arguments, they assign thematic roles, and they have a semantic content, possibly underspecified. The only difference with the other open-class categories like nouns, verbs or adjectives is that they do not have any morphology.