Lecture 1. Introduction
Материал из Wiki - Факультет компьютерных наук
Ekaterina Chernyak, Dmitry Ilvovsky
Содержание
Brief history of NLP
- January 7, 1954 — Georgetown experiment. Russian to English machine translation;
- 1957 — Noam Chomsky introduced "universal grammar";
- since 1961 — Brown Corpus;
- the late 1960's — ELIZA, a simulation of a psychotherapist;
- 1975 — Vector Space Model by Salton;
- up to the early 1980's — rule based approaches;
- after the early 1980's — machine learning, corpus linguistics;
- 1998 — Language Model by Ponte and Croft;
- since 1999 — topic modeling (LSI, pLSI, LDA, etc);
- 1999 — "Foundations of Statistical Natural Language Processing" by Manning and Shuetze;
- 2009 — "Natural Language Processing with Python" by Bird, Klein, and Loper.
Major tasks of NLP
- Machine Translation
- Text classification
- Sentiment analysis
- Spam filtering
- Classification by topic or by genre
- Text clustering
- Named entity recognition
- Question answering
- Automatic summarization
- Natural language generation
- Speech recognition
- Spell checking
- User study design and evaluation
NLP techniques
- The level of characters:
- Word segmentation
- Sentence breaking
- The level of words — morphology:
- Part of speech (POS) tagging
- Word sense disambiguation
- The level of sentences — syntax:
- Parsing
- The level of senses — semantics:
- Coreference resolution
- Discourse analysis
- Semantic role labeling
- Synonymy detection
Main problems
- Ambiguity
- Lexical ambiguity:
- Time flies like an arrow; fruit flies like a banana.
- Syntactic ambiguity
- Police help dog bite victim.
- Wanted: a nurse for a baby about twenty years old.
- Neologism: unfriend, retweet, instagram
- Different spelling: NY, New York City, New-York
- Non-standard language: HIIII, how are u? miss u SOOOO much:((((
About this course
It covers the following topics:
- Tokenization
- POS tagging
- Key word and phrase extraction
- Parsing
- Synonyms detection
- Language sources
- Topic modeling
- Text visualisation
You can try to use Python and R for various tasks.