NLP ?

• Natural Language is one of fundamental aspects of human behaviors.

• One of the final aim of human-computer communication.

• Provide easy interaction with computer

• Make computer to understand texts.

Major Disciplines Studying Language

Discipline Typical Problem

Linguists How do words from phrases and sentences?

Psycholinguists How do people identify the structure of sentences?

Philosophers What is meaning and how do words and sentences acquires it?

Computational Linguists

How is the structure of sentences identified?

Interaction Level

• The level that computer and human interact.

• NL used for make Interaction level near to human.

Human Computer

Command-lineNL UIGraphical UI

Interaction level

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Natural Language Processing (NLP)

Natural language processing concerns the development of computational models of aspects of human language processing such as :

• Reading and interpreting a textbook• Writing a letter• Holding a conversation• Translating a document• Searching for useful information

Such models are useful in order to write computer programs to perform useful tasks involving language processing and in order to develop a better understanding of human communication.

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Computational Lingusitics

This is the application of computers to the scientific study of human language.

This definition suggests that there are connections with Cognitive Science, that is to say, the study of how humans produce and understand language.

Computational Lingusitics

Historically, Computational Linguistics has been associated with work in Generative Linguistics and formerly included the study of formal languages (eg finite state automata) and programming languages.

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Natural Language Understanding

Distinguish a particular approach to Natural Language Processing.

The people using this title tend to lay much emphasis on the meaning of the language being processed, in particular getting the computer to respond to the input in an apparently intelligent fashion.

Natural Language Understanding

At one time, those who belonged to the Natural Language Understanding camp avoided the use of any syntactic processing, but textbooks that bear this title now include significant sections on syntactic processing, which suggests that the edge of the title has been rather blunted. (For instance, see Allen (1987; part 1).

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NLP History (1)

The first recognizable NLP application was a dictionary look-up system developed at Birkbeck College, London in 1948.

NLP from 1966-1980 Augmented Transition Networks

Case Grammar

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NLP History (2)

NLP from 1966-1980 Semantic representations

Schank and his workers introduced the notion of Conceptual Dependency, a method of expressing language in terms of semantic primitives. Systems were written which included no syntactic processing.

QuillianÕs work on memory introduced the idea of the semantic network, which has been used in varying forms for knowledge representation in many systems.

William Woods used the idea of procedural semantics to act as an intermediate representation between a language processing system and a database system.

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NLP History (3)

The key systems were: LUNAR: A database interface system that used ATNs and

Woods' Procedural Semantics. LIFER/LADDER: One of the most impressive of NLP systems.

It was designed as a natural language interface to a database of information about US Navy ships.

NLP from 1980 - 1990

- Grammar Formalisms

NLP from 1990- now

- Multilinguality and Multimodality

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NLP Applications

Applications can be classified in different ways, e.g. medium/modality; depth of analysis; degree of interaction

Text-based applications

NL Understanding

Dialogue Systems

Multimodal

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Text-based Applications

Processing of written texts such as books, news, papers, reports:

Finding appropriate documents on certain topics from a text database

Extracting information from messages, articles, Web pages, etc.

Text-based Applications

Translating documents from one language to another

Text summarization

Note: Not all such applications require NLP

Keyword based techniques can used for identifying particular subject areas, e.g. legal, financial, etc.

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NL Understanding

Other kinds of request require a deeper level of analysis

Find me all articles concerning car accidents involving more than two cars in Malta during the first half of 2001

Here the system must extract enough information to determine whether the article meets the criterion defined by the query.

NL- Understanding

A crucial characteristic of an understanding system is that it can compute some representation of the information that can be used for later inference

A crucial question for an NLP system is how much understanding is necessary to achieve the purpose of the system.

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Dialogue-based Applications

Dialogue-based applications involve man-machine communication

NL database query systems

Automated customer services, e.g. banking services

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Multimodal Applications

Involve two or more modalities of communication

Text

Speech

Gesture

Image

Text speech

Speech text

Multimodal document generation

Spoken translation systems

Spoken dialogue systems