March 1, 2009 Dr. Muhammed Al-Mulhem 1 ICS 482 Natural Language Processing INTRODUCTION Muhammed Al-Mulhem March 1, 2009

Dr. Muhammed Al-Mulhem 2 What is Natural Language Processing? The study of human languages and how they can be represented computationally and analyzed and generated algorithmically Studying NLP involves studying natural language, formal representations, and algorithms for their manipulation

March 1, 2009 Dr. Muhammed Al-Mulhem 3 What is Natural Language Processing? Building computational models of natural language comprehension and production Other Names: Computational Linguistics (CL) Human Language Technology (HLT) Natural Language Engineering (NLE) Speech and Text Processing

March 1, 2009 Dr. Muhammed Al-Mulhem 4 Morphological Analysis Individual words are analyzed into their components Morphological Analysis Individual words are analyzed into their components Syntactic Analysis Linear sequences of words are transformed into structures that show how the words relate to each other Syntactic Analysis Linear sequences of words are transformed into structures that show how the words relate to each other Discourse Analysis Resolving references Between sentences Discourse Analysis Resolving references Between sentences Pragmatic Analysis To reinterpret what was said to what was actually meant Pragmatic Analysis To reinterpret what was said to what was actually meant Semantic Analysis A transformation is made from the input text to an internal representation that reflects the meaning Semantic Analysis A transformation is made from the input text to an internal representation that reflects the meaning

March 1, 2009 Dr. Muhammed Al-Mulhem 5 Parsing (Syntactic Analysis) Assigning a syntactic and logical form to an input sentence –uses knowledge about word and word meanings (lexicon) –uses a set of rules defining legal structures (grammar) Example: ahmad ate the apple. S→ NP VP → ahmad VP → ahmad VP NP → ahmad ate NP → ahmad ate DET NP → ahmad ate the NP → ahmad ate the apple

March 1, 2009 Dr. Muhammed Al-Mulhem 6 Word Sense Resolution Many words have many meanings or senses We need to resolve which of the senses of an ambiguous word is invoked in a particular use of the word I made her duck. (made her a bird for lunch or made her move her head quickly downwards?)

March 1, 2009 Dr. Muhammed Al-Mulhem 7 I want to print Ali ’ s.init file I (pronoun) want (verb) to (prep) to(infinitive) print (verb) Ali (noun) ‘ s (possessive).init (adj) file (noun) file (verb) I (pronoun) want (verb) to (prep) to(infinitive) print (verb) Ali (noun) ‘ s (possessive).init (adj) file (noun) file (verb) Surface form stems

March 1, 2009 Dr. Muhammed Al-Mulhem 8 I (pronoun) want (verb) to (prep) to(infinitive) print (verb) Ali (noun) ‘ s (possessive).init (adj) file (noun) file (verb) I (pronoun) want (verb) to (prep) to(infinitive) print (verb) Ali (noun) ‘ s (possessive).init (adj) file (noun) file (verb) S NP VP NP VP S V PRO PREV ADJ N I want toprint Ali’s.initfile stems Parse tree

March 1, 2009 Dr. Muhammed Al-Mulhem 9 S NP VP NP VP S V PRO PREV ADJ N I want toprint Ali’s.initfile Parse tree I I want print Ali.init file who what who Who’s what type Semantic Net

March 1, 2009 Dr. Muhammed Al-Mulhem 10 I I want print Ali.init file who what who Who’s what type Semantic Net To whom the pronoun ‘I’ refers To whom the proper noun ‘Ali’ refers What are the files to be printed Execute the command lpr /ali/stuff.init Execute the command lpr /ali/stuff.init

March 1, 2009 Dr. Muhammed Al-Mulhem 11 Morphologi cal Analysis Syntactic Analysis Semantic Analysis Discours e Analysis Pragmati c Analysis Internal representatio n lexicon user Surface form Perform action stems parse tree Resolve references

March 1, 2009 Dr. Muhammed Al-Mulhem 12 The species of flies known as “time flies” like an arrow. Time passes along in the same manner as an arrow gliding through space. I order you to take timing measurements on flies, in the same manner as you would time an arrow. more than one meaning for the same sentence Time flies like an arrow

March 1, 2009 Dr. Muhammed Al-Mulhem 13 The boy saw the man on the mountain with a telescope Prepositional phrase attachment

March 1, 2009 Dr. Muhammed Al-Mulhem 14 Lexicon is a vocabulary data bank, that contains the language words and their linguistic information. There are many on-line lexicon WordNet is a lexical database that contains English vocabulary words COULD WE HAVE ONE FOR ARABIC? Lexicon is a vocabulary data bank, that contains the language words and their linguistic information. There are many on-line lexicon WordNet is a lexical database that contains English vocabulary words COULD WE HAVE ONE FOR ARABIC?

March 1, 2009 Dr. Muhammed Al-Mulhem 15 Simple Applications Word counters (wc in UNIX) Spell Checkers, grammar checkers Predictive Text on mobile handsets

March 1, 2009 Dr. Muhammed Al-Mulhem 16 Bigger Applications Intelligent computer systems NLU interfaces to databases Computer aided instruction Information retrieval Intelligent Web searching Data mining Machine translation Speech recognition Natural language generation Question answering

March 1, 2009 Dr. Muhammed Al-Mulhem 17 NLP Example: Chat with Alice =f5d922d97e345aa1&skin=custom_input =f5d922d97e345aa1&skin=custom_input A.L.I.C.E. (Artificial Linguistic Internet Computer Entity) is an award-winning free natural language artificial intelligence chat robot. The software used to create A.L.I.C.E. is available as free ("open source") Alicebot and AIML software.