2 chapter I. An overview of morphology

Morphological analysis

In natural language processing for Korean, Japanese, Chinese and other languages, morphological analysis is the process of segmenting a sentence into a row of morphemes. Morphological analysis is closely related to part-of-speech tagging, but word segmentation is required for these languages because word boundaries are not indicated by blank spaces.
The purpose of morphological analysis is to determine the minimal units of meaning in a language or morphemes by using comparisons of similar forms. For example, comparing forms such as “She is walking” and “They are walking” rather than comparing any of the previous sentences with something completely different like “You are reading”. Thus, we can effectively break down the forms in parts and distinguishing the different morphemes. Similarly, keep in mind that the meaning and the form are equally important during the identification of morphemes. For instance, agent and comparative morphemes illustrate this point. An agent morpheme is an affix like -er that transforms a verb into a noun (e.g. teach ⇒ teacher). On the other hand, –er can also be a comparative morpheme that changes an adjective into another degree of the same adjective (e.g. small ⇒ smaller). In this case, the form is the same, but the meaning of both morphemes is different. Also, the opposite can occur in which the meaning is the same but the form is different.

Changing definitions of morpheme

In generative grammar, the definition of a morpheme depends heavily on whether syntactic trees have morphemes as leaves or features as leaves.

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  Direct surface to syntax mapping LFG – leaves are words
  
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  Direct syntax to semantics mapping
  
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    Leaves in syntactic trees spell out morphemes: Distributed morphology – leaves are morphemes
    
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    Branches in syntactic trees spell out morphemes: Radical Minimalism and Nanosyntax – leaves are "nano" morpho-syntactic features
    

Given the definition of morpheme as "the smallest meaningful unit" Nanosyntax aims to account for idioms where it is often an entire syntactic tree which contributes "the smallest meaningful unit." An example idiom is "Don't let the cat out of the bag" where the idiom is composed of "let the cat out of the bag" and that might be considered a semantic morpheme, which is composed of many syntactic morphemes. Other cases where the "smallest meaningful unit" is larger than a word include some collocations such as "in view of" and "business intelligence" where the words together have a specific
Morphemes can be classified from different view-points:
1. functional
2. number correlation between form and content
From the point of view of function they may be lexical and grammatical. The lexical morphemes are those that express full lexical meaning of their own and are associated with some object, quality, action, number of reality, like: lip, red, go, one and so on. The lexical morphemes can be subdivided into lexical - free and lexical - bound morphemes. The examples given above are free ones; they are used in speech independently. The lexical-bound ones are never used independently; they are usually added to some lexical-free morphemes to build new words like- friend-ship, free-dom, teach-er, spoon-ful and so on. Taking into account that in form they resemble the grammatical inflections they may be also called lexical - grammatical morphemes. Thus lexical - bound morphemes are those that determine lexical meanings of words but resemble grammatical morphemes in their dependence on lexical – free morphemes.
The lexical - bound morphemes are means to build new words.
The grammatical morphemes are those that are used either to connect words in sentences or to form new grammatical forms of words. The content of such morphemes are connected with the world of reality only indirectly therefore they are also called structural morphemes, e.g., shall, will, be, have, is, -
(e)s, -(e)d and so on. As it is seen from the examples the grammatical morphemes have also two subtypes: grammatical - free and grammatical - bound. The grammatical - free ones are used in sentences independently (I shall go) while grammatical - bound ones are usually attached to some lexical - free
morphemes to express new grammatical form, like: girl's bag, bigger room, asked.
From the point of view of number correlation between form and content there may be overt, zero, empty and discontinuous morphemes.
By overt morpheme the linguists understand morphemes that are represented by both form and content like: eye, bell, big and so on.
Zero morphemes are those that have (meaning) content but do not have explicitly expressed forms. These morphemes are revealed by means of comparison:
ask – asks
high -higher