morphological analysis paradigm based approach

1. Language processing (HUL455)
MORPHOLOGICAL
ANALYSIS
-JINIA RAO & ASHISH KASHYAP

2. CONTENTS
• Morphology & its types.
• Approaches to Morphology
• Morpheme based morphology
• Morphological Analysis and its need.
• Morphological Generation and Analysis using
Paradigms
• Problems in Morphological Analysis.
• Bibliography.

3. MORPHOLOGY
• The study of word formation – how words are
built up from smaller pieces.
• Identification, analysis, and description of the
structure of a given language's MORPHEMES
and other linguistic units, such as root
words, affixes, parts of
speech, intonations and stresses, or
implied context.

4. Examples
• Washing= wash + ing
• Browser= browse + er
• Rats= rat + s

5. Types of Morphology
• Inflectional morphology:-modification of a
word to express different grammatical
categories. Examples- cats, men etc.
• Derivational Morphology:- creation of a new
word from existing word by changing
grammatical category. Examples- happiness,
brotherhood etc.

6. APPROACHES TO MORPHOLOGY
There are three principal approaches to
morphology
• Morpheme based morphology
• Lexeme based morphology
• Word based morphology

7. Morpheme-based morphology
• Word forms are analyzed as arrangements
of morphemes.
• Morphemes- smallest linguistic unit with a
grammatical function.

8. Lexeme based Morphology
• Lexeme-based morphology usually takes what
is called an "item-and-process" approach.
• Instead of analyzing a word form as a set of
morphemes arranged in sequence, a word
form is said to be the result of applying rules
that alter a word-form or stem in order to
produce a new one

9. Word based Morphology
• Word-based morphology is (usually) a word-
and-paradigm approach.
• Instead of stating rules to combine
morphemes into word forms, or to generate
word forms from stems, word-based
morphology states generalizations that hold
between the forms of inflectional paradigms

10. MORPHOLOGICAL ANALYSIS
• Analyzing words into their linguistic
components (morphemes).
• Ambiguity: More than one alternatives
flies fly VERB + PROG
fly NOUN + PLU

11. Expected Output
Input Morphologically analyzed output
Cats Cat+ N+ PL
Cat Cat + N + SG
Cities City + N + PL
Geese Goose + N + PL
Goose Goose + N + SG OR Goose + V
Gooses Goose + V + 3SG
Merging Merge + V + PresPart
Caught Catch + V + PastPart
Caught Catch + V + Past

12. NEED FOR MORPHOLOGICAL ANALYSIS
• Wastage of memory in exhaustive lexicon.
• Failure to depict linguistic generalization-
necessary to understand an unknown word.
• Morphologically rich and productive
languages might be problematic.

13. MORPHOLOGICAL ANALYSIS
USING PARADIGMS
• Most NLP systems use simple linguistic
theories for morphological analysis.
• Most NLP systems widely use this approach.

14. • Words are related to each other by analogical
rules.
• Words can be categorized based on the
pattern they fit into.
• Applicable both to existing words and to new
ones.
• Application of a pattern different from the
one that has been used - give rise to a new
word
• Examples:-older replacing elder .

15. Procedure and Algorithm
• A language expert provides different tables of
word forms covering the words in the entire
language.
• The roots follow the pattern( or paradigm )
implicit in the table for generating their word
forms.
• Examples

16. Continued..
EACH ENTRY IN THE TABLE SHOWS THE NUMBER OF
CHARACTERS TO BE DELETED FROM
CASE
Number Direct Oblique
Singular LADKAA LADAKE
Plural LADAKE LADAKON
CASE
Number Direct Oblique
Singular (0,ø) (1,e)
Plural (1,e) (1,ON)

17. Continued…
The table can be expressed in terms of an algorithm, which is as
follows:-
ALGORITHM 1: Forming paradigm table
PURPOSE: To form paradigm table from word forms table for a
root
INPUT: Root r, Words forms table WFT (with labels for rows and
columns)
OUTPUT: Paradigm table PT
ALGORITHM:
1. Create an empty table PT of the same dimensionality, size and
labels as the word forms table WFT

18. Continued…
2. For every entry w in WTF, do
If w=r
then store “(0, Ø)” in the corresponding
position in PT
else begin
let i be the position of the first
characters in w and r which are
different
store (size(r)-i+1,suffix(i,w)) at the
corresponding position in PT
3. Return PT

19. Generation of a Word Form
ALGORITHM 2: Generating a word form
PURPOSE: To generate a word form given a root and
desired feature values.
INPUT: Root r, Feature values FV
USES: Paradigm tables, Dictionary of roots DR,
dictionary of indeclinable words DI
OUTPUT: Word w
ALGORITHM:
1. If root r belongs to DI then return( words
stored in DI for r irrespective of FV)

20. Continued…
2. let p = paradigm type of r as obtained from
DR
3. let PT = paradigm table for p.
4. let (n,s) = entry in PT for feature values
FV
5. w := r minus n characters at the end
6. w := w plus suffix s
END ALGORITHM

21. PROBLEMS IN MORPHOLOGICAL
ANALYSIS
• False Analysis
• Productivity
• Bound base morphemes

22. False analysis
Words such as hospitable, sizeable.
• They don’t have the meaning “to be able”
• They can not take the suffix -ity to form a
noun
• Analyzing them as the words containing suffix
-able leads to false analysis

23. PRODUCTIVITY
• Property of a morphological process to give rise
to new formations on a systematic basis.
Exceptions to the above rule.
• Peaceable
• Actionable
• Companionable

24. Bound Base Morphemes
• Occur only in a particular complex word.
• Do not have independent existence.
• Words such as feasible, malleable
• -able has the regular meaning “be able”
• -ity form is possible
• Base words don’t exit independently
base
(nonexistent)
morpheme
(known)
Compound

25. REFERENCES
• “Linguistics, An Introduction to Language and
Communication” by Adrian Akmajian, Richard A.
Demers, Ann K. Farmer and Robert M. Harnish (5th
Edition)
• SPEECH and LANGUAGE PROCESSING, An Introduction
to Natural Language Processing,
Computational Linguistics, and Speech Recognition by
Daniel Jurafsky and James H. Martin (Second Edition)
• “Natural Language Processing- a Paninian perspective”
by Akshar Bharati, Vineet Chaitanya, Rajeev Sangal.

26. THANKYOU!!!