PROBLEMS WITH NLP NLP How to communicate with

PROBLEMS WITH NLP

NLP • How to communicate with computer? • NLP chooses the option of communicating with computer in natural language

COMPONENTS OF NLP • Natural language understanding • Natural language generation

PROBLEMS WITH NLP • Ambiguity • Incompleteness • Inaccuracy • Imprecision

AMBIGUITY • Natural languages are inherently ambiguous. • Humans generally manage to pick out the intended meaning from a set of possible interpretations, but hard for them as well in some situations. • Due to their limited ‘knowledge’ and inability to get their bearings in complex situations, understanding natural language is a difficult task for computers.

AMBIGUITY: A DEFINITION • An input is termed to be ambiguous if there are multiple alternative linguistic structures that can be built for it. • For example: – “I made her duck”. • This simple sentence could have five meanings.

AMBIGUITY EXAMPLE “I made her duck”. 1. I cooked a duck belongs to her. 2. I cooked a duck for her. 3. I created the plaster duck she owns. 4. I caused her to quickly lower head or body. 5. I turned her into a duck (by magic).

AMBIGUITY (CONT. ) These meanings are caused by a number of ambiguities, i. e. 1. The words her and duck are syntactically ambiguous. 2. The word make is semantically ambiguous 3. ‘I’ or ‘eye’ and ‘made’ or ‘maid’ (if the sentence is a spoken one)

TYPES OF AMBIGUITIES • Following are the various types of ambiguities: – Lexical or Semantic ambiguity – Syntactic or Structural ambiguity – Pragmatic ambiguity – Referential ambiguity – Transient ambiguity

LEXICAL AMBIGUITY (SEMANTIC AMBIGUITY) • An ambiguity caused when a word has more than one meaning. – For example: • ‘The wrestlers entered the ring’. – Ring can be a proposed area for wrestling. – Ring can be a golden ring wrapped around a finger. – "You know, somebody actually complimented me on my driving today. They left a little note on the windscreen; it said, 'Parking Fine. ' So that was nice. "(English comedian Tim Vine)

SYNTACTIC AMBIGUITY • Syntactic ambiguity occurs when a phrase or sentence has more than one underlying structure. • Syntactic ambiguity arises not from the range of meanings of single words, but from the relationship between the words and clauses of a sentence, and the sentence structure implied thereby.

SYNTACTIC AMBIGUITY (CONT. . ) • Consider the following phrases and sentences: – ‘Pakistani history teacher', – ‘tall men and women‘, – 'The girl hit the boy with a book‘, – 'Visiting relatives can be boring'. – “Put the box on the table by the window in the kitchen” • 1. Put the box [ which is on the table by the window] in the kitchen. • Put the box on the table[which is by the window in the kitchen] • These ambiguities are said to be structural because each such phrase can be represented in two or more structurally different ways.

SYNTACTIC AMBIGUITY (CONT. . ) • The possible meanings for ‘Time flies like an arrow’ are: – 1. Time goes by as quickly as an arrow. – 2. . Someone or something named "Time" flies in a way similar to an arrow. E. g. • "Mr. Time flies an airplane fast and straight. "

PRAGMATIC AMBIGUITY • Occurs when speaker and listener don’t agree on same principals of co-operative communication. – For example: • Can you pass the salt • The police are coming • The six Wives of Henry VIII, 1. Do you have the physical ability to pass the salt or will you pass the salt (intention) or please give me the salt. 2. Does this mean they are coming for you/me, they are coming down the road, they are always present etc?

• • • The Six Wives of Henry VIII may refer to: Wives of Henry VIII, the spouses of King Henry VIII of England The Six Wives of Henry VIII (BBC TV series), a 1970 BBC TV miniseries The Six Wives of Henry VIII (documentary), a 2001 documentary series by David Starkey The Six Wives of Henry VIII, a 2016 miniseries presented and partially narrated by Dan Jones and Susannah Lipscomb • Henry VIII and His Six Wives (film), a 1972 film adaptation of the 1970 BBC TV miniseries • The Six Wives of Henry VIII (album), a 1973 album by Rick Wakeman – The Six Wives of Henry VIII: Live at Hampton Court Palace, a live album, released in 2009, based on the 1973 album by Rick Wakeman • The Six Wives of Henry VIII (book), a 1991 book by Alison Weir • The Six Wives of Henry VIII, a 1993 book by Antonia Fraser

EXAMPLES-PRAGMATICS AMBIGUITY • ‘The cops are coming’ can be an assertion, a warning, or an expression of relief. • ‘I’m sorry you were raised so badly’ can be an insult or an apology. • ‘Can you pick me up later? ’ can function as a request or a question or both.

REFERENTIAL AMBIGUITY • May be unclear what objects are referred to, also called discourse ambiguity • Examples – 1) He drove the car over the lawn mower, but he wasn't hurt. – 2) Bob waved to Jim in the hallway between class. He smiled. – 3) Ali is helping Majid. He is very happy

TRANSIENT AMBIGUITY • Arises due to incompleteness of the sentence. • Examples – 1) the old train • The sentence is ambiguous until it is completed – The old train the young

INCOMPLETENESS OR CONTEXT • Natural languages are context sensitive • The sentences with not all the information explicitly mentioned can still hold the information, which a human can extract. • This will not be possible for the computer. • Example. – Ali went to restaurant and he ordered the meal; but when he was paying he noticed that he was running out of money – Did Ali eat his meal?

INACCURACY • A sentence with spelling or grammatical mistakes can be understood by the humans unlike computers. • Examples

CAN YOU READ IT? • A vheclie epxledod at a plocie cehckipont near the UN haduqertares in Bagahdd on Mnoday kilinlg the bmober and an Irqai polcie offceir. • Big ccunoil tax ineesacrs tihs yaer hvae seezueqd the inmcoes of mnay pneosenirs.

IMPRECISION • The vague/inexact statements and words • Long time, very sweet, very slow,