2. Objectives:
At the end of the lesson we would be able to;
1. understand the importance of the written
language in the 21st century education and its
meaning,
2. appreciate the valuable factors involve in
processing written language.
3. What is written language?
the representation of a language by means
of a writing system. Written language is an
invention in that it must be taught to
children; children will pick up spoken
language (oral or sign) by exposure
without being specifically taught.
4. Processing of Written Language
One of the most difficult topics is NLP
(Natural Language Processing) : removal of
the language barrier between people. This
involves communicating with application
programs or expert systems in the most
natural and efficient format. Pattern
recognition in speech and visual scene
analysis are therefore significant. Success in
natural language understanding has been
slow in coming and achieved at great cost
and effort.
5. The goal of natural language translation was
one of the first attempted by Artificial
Intelligence (AI) researchers, and failure to
reach it proved to be one of AI's greatest
disappointments. However, analysis of past
failures allowed progress has been made to
generalise this "translation" machine.
6. Ways of Communication of Languages
The majority of human linguistic
communication occurs as speech. Written
language was only a recent invention and
plays a less central role. However,
processing written language (assuming an
unambiguous representation) is easier than
processing speech in general. For example,
building a program that understands speech
requires all facilities of a written language
understand as well as enough knowledge to
handle noise and ambiguities of audio signal.
7. Thus it is useful to split the problem into
two subtasks:
1. Processing written text using;
a. Syntactic
b. Lexical
c. Semantic knowledge of language
2. Processing spoken language using;
all information needed above, and
additional knowledge about
phonology.
8. Steps in the Process
One pitfall in processing language is that
it is tempting to define the language simply
as a set of strings, without reference to
understanding the context. However, in
order to increase realism and accuracy, we
must represent the language as a pair:
(source language, target representation).
The target representation would be chosen
relevant to the situation. Hence it is possible
to depict this as a mapping from the piece of
language to some representation.
9. In overview, to achieve this we need to
define precisely what the underlying
task and target representation would
look like.
1. Morphological Analysis
a. Singleton words are analysed into
their respective components
b. Non-word tokens (e.g. punctuation)
are categorised separately.
10.
11. 2. Syntactic Analysis
a. Structure holds linear sequences of
related words
b. Word sequence is rejected if it
violates the language rules for how
words may be combined For
example, an English analyser would
reject: "Girl the walk computer do."
12.
13.
14. 3. Semantic Analysis
a. Structures created by syntactic analyser are
assigned meanings
b. Mapping exists between syntactic structures
and objects in task domain.
c. Structures with no mappings may be
rejected (semantically anomalous). For
example, the sentence: "Colorless green
ideas sleep furiously" [Chomsky, 1957]
15.
16. 4. Discourse Integration
a. Meaning of an individual sentence
could influence other sentences
that precede or follow it.
For example, the word "it" in the
sentence: "George needed it" depends
on the preceding context; while the
word "George" could influence the
meaning of later sentences, such as
"He always laughs".
17. 5. Pragmatic Analysis
a. Structure representing what was
said is interpreted to determine
what is required to be done.
b. Application of a set of rules that
characterise co-operative
dialogues.
c. Translation from knowledge-based
representation to a command
executed by the system.
18.
19. Complete separation of these
phases is difficult. These steps all
interact in some way, and can be
processed sequentially or in
parallel. However, if there is
dependence from one phase to
another, it is critical to process in
an order which satisfies the overall
performance.