Morphological dictionary
Encyclopedia
In the field of computational linguistics, a morphological dictionary is a file that contains correspondences between surface form and lexical forms of words. Surface forms of words are those found in any text. The corresponding lexical form of a surface form is the lemma followed by grammatical information (for example the part of speech, gender
and number
). In English houses is a surface form of the noun house. The lexical form would be "house", noun, plural. There are two kinds of morphological dictionaries: aligned and non-aligned.
(o,o) (u,u) (s,s) (e,e) (s,), (θ,)
Where θ is the empty symbol and signifies "noun", and signifies "plural".
In the example the left hand side is the surface form (input), and the right hand side is the lexical form (output). This order is used in morphological analysis
where a lexical form is generated from a surface form. In morphological generation this order would be reversed.
Formally, if Σ is the alphabet of the input symbols, and
is the alphabet of the output symbols, an aligned morphological dictionary is a subset 
, where:
is the alphabet of all the possible alignments including the empty symbol. That is, an aligned morphological dictionary is a set of string in
.
of pairs of input and output strings. A non-aligned morphological dictionary would represent the previous example as:
It is possible to convert a non-aligned dictionary into an aligned dictionary. Besides trivial alignments to the left or to the right, linguistically motivated alignments which align characters to their corresponding morphemes are possible.
If we define the set
of input words such that 
, the correspondence funcion would be 
defined as 
.
Grammatical gender
Grammatical gender is defined linguistically as a system of classes of nouns which trigger specific types of inflections in associated words, such as adjectives, verbs and others. For a system of noun classes to be a gender system, every noun must belong to one of the classes and there should be...
and number
Grammatical number
In linguistics, grammatical number is a grammatical category of nouns, pronouns, and adjective and verb agreement that expresses count distinctions ....
). In English houses is a surface form of the noun house. The lexical form would be "house", noun, plural. There are two kinds of morphological dictionaries: aligned and non-aligned.
Aligned morphological dictionaries
In an aligned morphological dictionary, the correspondence between the surface form and the lexical form of a word is aligned at the character level. Continuing with the previous example, we have:(o,o) (u,u) (s,s) (e,e) (s,
Where θ is the empty symbol and
In the example the left hand side is the surface form (input), and the right hand side is the lexical form (output). This order is used in morphological analysis
Morphological analysis
Morphological Analysis or General Morphological Analysis is a method developed by Fritz Zwicky for exploring all the possible solutions to a multi-dimensional, non-quantified problem complex.-Overview:...
where a lexical form is generated from a surface form. In morphological generation this order would be reversed.
Formally, if Σ is the alphabet of the input symbols, and
is the alphabet of the output symbols, an aligned morphological dictionary is a subset , where:is the alphabet of all the possible alignments including the empty symbol. That is, an aligned morphological dictionary is a set of string in
.Non-aligned morphological dictionary
A non-aligned morphological dictionary is simply a set of pairs of input and output strings. A non-aligned morphological dictionary would represent the previous example as:It is possible to convert a non-aligned dictionary into an aligned dictionary. Besides trivial alignments to the left or to the right, linguistically motivated alignments which align characters to their corresponding morphemes are possible.
Lexical ambiguities
Frequently there exists more than one lexical form associated with a surface form of a word. For example "house" may be a noun in the singular, /haʊs/, or may be a verb in the present tense, /haʊz/. As a result of this it is necessary to have a function which relates input strings with their corresponding output strings.If we define the set
of input words such that , the correspondence funcion would be defined as .