also been argued that adpositions (cover term for prepositions and postpositions) are not part of the [+/-N] [+/-V] system as shown above. This is because they resist being part of a single class category, like nouns, verbs and adjectives do. This argument also posits that some appositions may behave as part of this type of categorization, but not all of them do. There are three main hypotheses regarding the syntactic categories of words. The first one is the Strong Lexical hypothesis, which states that verbs and nouns are inherent in nature, and when a word such as "walk" in English can surface as either a noun or a verb, depending on the speaker's intuitions of what the meaning of the verb is. This means that the root "walk" in English has two separate lexical entries:walk N <[AP]> an act or instance of going on foot especially for exercise or pleasurewalk V <[DPtheme]> to move along on foot : advance by steps Syntactic analysis This analysis states that the category is determined by syntax or context. A root word is inserted into the syntax as bare and the surrounding syntax determines if it will behave as a verb or a noun. Once the environment has determined its category, morphological inflections also surface on the root according to the determined category. Typically, if the element before it is a determiner, the word will surface as a noun, and if the element before it is a tense element, the root word will surface as a verb. The example in the photo shows an example from Italian. The root of the word is cammin- ("walk"). This word could surface as either a noun or verb. The first tree shows that when the element before is a D "una", the root will be an N and the following morphology will inflect -ata which is the correct full orthography for the noun "walk" in Italian. The tree on the right shows a similar process but in the environment where the root follows a tense element, and the morphology inflects -o as a suffix, which makes the verb surface not only as a verb, but as discussed before in person agreement, also shows that this is the first person present form of the verb ("I walk"). Combinatorial analysis Syntactic decomposition for categorization of parts of speech includes an explanation for why some verbs and nouns have a