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CS344: Introduction to Artificial Intelligence
Pushpak BhattacharyyaCSE Dept., IIT B bIIT Bombay
Lecture 32: Information Retrieval: Basic t d M d lconcepts and Model
The elusive user satisfactionThe elusive user satisfaction
RankingRanking
CorrectnessCorrectnessof
Query ProcessingCoverage
I d iNER
StemmingMWE
CrawlingIndexing
MWE
Q I di T ib i L tiQuery: Indian Tribes in Latin AmericaAmerica
GoogleIndians of Latin America: an exhibition of materials in the Lilly ...Lilly Library: Latin American mss. Brazil. A large map in colors, this locates the course of rivers, towns, mountain ranges, and Indian tribes. ...www.indiana.edu/~liblilly/etexts/ila/ - 241k - Cached - Similar pages - Note thisIndigenous peoples of the Americas - Wikipedia, the free encyclopediaAmerican Indian creation legends tell of a variety of originations of that it had confirmed the presenceAmerican Indian creation legends tell of a variety of originations of ..... that it had confirmed the presence of 67 different uncontacted tribes in Brazil, ...en.wikipedia.org/wiki/Indigenous_peoples_of_the_Americas - 178k - Cached - Similar pages - Note thisCognition :: Giving Technologies New MeaningThe volumes that Farabee produced from his travels include Indian Tribes of Eastern Peru ... motor vehicles that are lemons Indian tribes of Latin America ...wikipedia cognition com/?num=10&from val Indian%20tribes%20of%20Latin%20Ame - 54k -wikipedia.cognition.com/?num=10&from_val...Indian%20tribes%20of%20Latin%20Ame... - 54k -Cached - Similar pages - Note thisTop 25 American Indian Tribes for the UnitedTop 25 American Indian Tribes for the UnitedStates: 1990 and 1980--Con. ... 16028 73.0 Canadian and Latin American... 19375 248.3 Chickasaw. ...www.census.gov/population/socdemo/race/indian/ailang1.txt - 6k - Cached - Similar pages - Note thisTen Largest American Indian Tribes 2000 Infoplease comTen Largest American Indian Tribes, 2000 Infoplease.comLatin American Indian, 180940. Choctaw, 158774. Sioux, 153360 ... American Indian and Alaska Native Population by Selected Tribes, Census 2000 ...www.infoplease.com/ipa/A0767349.html - 29k - Cached - Similar pages - Note thisThe Indian Tribes of North America by John R. Swanton at Questia ...Read the complete book The Indian Tribes of North America by becoming a ..... Sao Paulo recently elected its must cope with demands by Latin America forits...must cope with demands by Latin America for ...www.questia.com/library/book/the-indian-tribes-of-north-america-by-john-r-swanton.jsp - Similar pages- Note this
Yahoodifferent indian tribes of latin america,More...WEB RESULTSSouth America DailyIndian Pepper Photos Prices Spices. The Times of India ... Archaeologists unearth ancient tribe members sacri London ... Iran and the left in Latin America ...www.wn.com/LatinAmerica - 192kwww.wn.com/LatinAmerica 192kNative American Indian Cultures - Mexico, South AmericaAlso, many of the Yanomamo tribe are losing their members and culture by ... of Amazon Indian tribal art in the world, with over 75 tribesrepresented. ...indian-cultures.com - CachedNative American Indian Cultures - linksNorth American Tribes. rednation.org - RedNation of the Cherokee. Meso and Latin American Indians ... Human Rights in Latin America...
i di lt /C lt /Li k ht l C h dwww.indian-cultures.com/Cultures/Links.html - CachedIndigenous peoples of the Americas - Wikipedia, the free encyclopedia... in America, particularly with regards to native Indians. ... Uncontacted Indian tribe found in Brazil's Amazon. The Peopling of the American Continents ...en.wikipedia.org/wiki/Indigenous_peoples_of_the_Americas - 179k - CachedNative American Images - American Indian North America Tribe MapAmerican Indian North America Tribe Map. Click here to view more images ... Medal | History Hotline | Iraqi War | Korean War | LatinAmericans | Medal of ...|www.nativeamericans.com/NativeAmericanImages6.htm - CachedResources forNumbers of Native Americans or Indians in Latin America: 39,442,000 million ... Indian Tribes in Latin America - Latin American Indian Population - Up date ...www.xmission.com/~amauta/population.htm - CachedIndian tribe found in Brazil's Amazon - Boston.comLatin America/Caribbean. Indian tribe found in Brazil's Amazon ... Uncontacted tribes are usually discovered when loggers and ranchers encroach onencroach on ...boston.com/news/world/latinamerica/articles/2007/06/01/.../ News
AltaVistaLatin AmericaCompare airfare prices from over 120 top websites and save up to 70%.Flights.SideStep.com
Regional Telecom Statistics & ForecastsFixed, mobile, Internet, broadband telecom statistics and forecasts.www.hottelecom.com
AltaVista found 4,520,000 results
South America DailyIndian Pepper Photos Prices Spices. The Times of India ... Archaeologists unearth ancient tribe members sacri London ... Iran and the left in Latin America...www.wn.com/LatinAmerica More pages from wn.com
Native American Indian Cultures - Mexico, South AmericaNative American Indian Cultures Mexico, South AmericaAlso, many of the Yanomamo tribe are losing their members and culture by ... of Amazon Indian tribal art in the world, with over 75 tribes represented. ...indian-cultures.com More pages from indian-cultures.com
Indian tribes in Suriname cross borders - Boston.comDays of rain near Suriname's southern border have deluged Amerindian farmland, ... Latin America/Caribbean. Indian tribes in Suriname cross borders ...www.boston.com/news/world/latinamerica/articles/2006/05/12...in_suriname_cross_borders More pages from boston.com
Indigenous peoples of the Americas - Wikipedia, the free encyclopedia... in America, particularly with regards to native Indians. ... Uncontacted Indian tribe found in Brazil's Amazon. The Peopling of the American Continents ...en.wikipedia.org/wiki/Indigenous_peoples_of_the_Americas More pages from en.wikipedia.org
Native American Images - American Indian North America Tribe MapAmerican Indian North America Tribe Map. Click here to view more images ... Medal | History Hotline | Iraqi War | Korean War | Latin Americans | Medal of ...www.nativeamericans.com/NativeAmericanImages6.htm More pages from nativeamericans.com
MSNNative American Images - American Indian North America Tribe MapNative American Images American Indian North America Tribe Map Click here to view more images ... History Hotline | Iraqi War | Korean War | Latin Americans ...
www.nativeamericans.com/NativeAmericanImages6.htm Cached page
Resources for152t ) P (126t ) P (67t ) S i (10t ) d V l (331t ) (t th d) I di T ib i L ti... 152t.), Panama (126t.), Paraguay (67t.), Surinam (10t.), and Venezuela (331t.) (t.=thousand). - Indian Tribes in Latin
Americawww.xmission.com/~amauta/tribes.htm Cached page
Latin America Community Assistance Foundation - LACAThe Tarahumara Indians are the most primitive of all Indian tribes in North America, and are the least touched by modern society.
www lacafoundation org/?page id 58www.lacafoundation.org/?page_id=58 Cached page
Latin America Tour Set for Curtis Photos of North America Tribes28 September 2005. Latin America Tour Set for Curtis Photos of North America Tribes. Famed photographer recorded Indian tribal life in 19th, early 20th century
www.america.gov/st/washfile-english/2005/September/20050928134700GLnesnoM0.2225763.htmlLatin America // CurrentC t TV L ti A i t di l L ti A i t i d f th A j l l d fli tCurrent TV Latin America category, discover popular Latin America stories, news and ... of the Amazon jungle, a land conflict between rice farmers and a handful of Indian tribes ...
current.com/topics/75844112_latin_america Cached page
Bloomberg.com: Latin AmericaMay 30 (Bloomberg) -- Brazil's National Indian Foundation has discovered an Indian tribe in the Amazon that hasn't had contact with civilization in a rare sighting of the few ...
bl b / / ? id 20601086& id S j5 fHW CQ& f l ti iwww.bloomberg.com/apps/news?pid=20601086&sid=aSrj5wfHW.CQ&refer=latin_america
Personalized focused search (wikipedia.cognition)
Indian Latin-America tribe: 249 files William Curtis FarabeeThe volumes that Farabee produced from his travels include Indian Tribes of Eastern Peru based on his first trip in 1906-1908 (Obituary, 1925).Direct link (no highlighting)Mexican TexasSettlers were empowered to create their own militias to help control hostile Indian tribes. Texas faced raids from both the Apache andSettlers were empowered to create their own militias to help control hostile Indian tribes. Texas faced raids from both the Apache and Comanche tribes, [...]Direct link (no highlighting)Temecula, CaliforniaThe Luiseo and Cahuilla tribes were involved, rather bloodily, in the local battles of the Mexican-American War during the following years. Direct link (no highlighting)Kaweah Indian NationRecently, scam artists have sold purported citizenships in the non-recognized tribe, particularly to Mexican nationals who have entered the US ill ll 1 [ ]illegally.1 [...]Direct link (no highlighting)Flag of Puerto RicoThe tribal nation flag of the Jatibonicu Taino Indians of Borikn, represents the Jatibonicu Taino tribe's original pre-Columbian territories of [...]Direct link (no highlighting)Maina IndiansThe Maina Indians are a group of tribes constituting a distinct linguistic stock, the [...] along the north bank of the Maran River in South AmericaAmericaDirect link (no highlighting)Erie (tribe)^ Ebooks by Google: "Handbook of American Indians North of Mexico" By Frederick Webb Hodge http://books.google.com/books?Direct link (no highlighting)Miccosukee[1] Other members went on to form the Miccosukee Tribe of Indians of Florida, which was not recognized by Fidel Castro's Cuban government in 1959. The [...]Direct link (no highlighting)New Tribes MissionIn Paraguay in 1979 and 1986, New Tribes Mission was accused of assisting in the forcible contact of nomadic Ayoreo Indians.Direct link (no highlighting)
Example: Semantically precise search for relations/events
Query: afghans destroying opium poppiesQ y fg y g p p pp
India Wide Cross Lingual I f ti A (CLIA)Information Access (CLIA)EndeavourEndeavour
MotivationEnglish still the most dominant language on the web
Contributes 72% of the content
Number of non-English users gsteadily rising all over the worldEnglish penetration in IndiaEnglish penetration in India
Estimated to be around 3-4%Mostly the urban educated classclass
Need to enable access to above information through local languages
Cross Language Information Retrieval (CLIR)
Crawled andTarget Language Index Crawled and Indexed
Web Pages
Target Language Indexin English
Hindi Query
CLIR Engine
T I f i
CLIR Engine
Target Informationin EnglishLanguage
Resources
| -
Ranked List of Results
| Result Snippets
in Hindi
Challenges involved in CLIAChallenges involved in CLIAIndexing, retrieval and ranking of multilingual documentsWeb data is not clean and regular
Different font encodings some of them proprietarySpelling variations very commonSpelling variations very commonDifferent document encodings
Language identification needed to invoke appropriate l llanguage analyzersInvolves a number of fundamental NLP research problems like query disambiguation, machine p q y gtransliteration, named-entity recognition, multi-word recognition
Cross Language Information Access (CLIA) Consortia Project
Indian Language CLIR Engine under developmentg g g pInput Six Indian Languages (Hindi, Bengali, Telugu, Tamil, Marathi and Punjabi) Output Hindi, English and Input Language of Queryp , g p g g Q yDomains Tourism (Current Release)
Involves 10 academic institutes all over the country: IITs, Indian Statistical Institute CDAC Anna UniversityIndian Statistical Institute, CDAC, Anna University, Jadavpur University
IIT Bombay Overall co-ordinatorResponsible for Hindi Marathi language verticalsResponsible for Hindi, Marathi language verticals
Includes full-fledged search featuresSnippet translationSummary generationInformation Extraction
Portal
Public portal released at http://www clia iitb ac in/clia-beta-ext/ inhttp://www.clia.iitb.ac.in/clia-beta-ext/ in September 2009. (Outside IITB)Public portal released atPublic portal released at http://www.clia.iitb.ac.in:8080/clia-beta-ext/ in September 2009. (Inside IITB)
Recent Press CoverageRecent Press Coverage
Hindustan Times
IR BasicsIR Basics
(mainly from R. Baeza-Yates and B. Ribeiro-Neto. Modern Information RetrievalAddison-Wesley, Wokingham, UK, 1999.
andChristopher D. Manning, Prabhakar Raghavan and Hinrich p g, gSchtze, Introduction to Information Retrieval, Cambridge
University Press. 2008. )
Definition of IR Model
An IR model is a quadrupul[D, Q, F, R(qi, dj)][ , Q, , (qi, j)]
Where,D: documentsD: documentsQ: QueriesF: Framework for modeling document queryF: Framework for modeling document, query and their relationshipsR(.,.): Ranking function returning a real no.R(.,.): Ranking function returning a real no. expressing the relevance of dj with qi
Index Terms
Keywords representing a documentSemantics of the word helps rememberSemantics of the word helps remember the main theme of the documentGenerally nounsGenerally nounsAssign numerical weights to index
d hterms to indicate their importance
IntroductionDocs Index TermsIndex Terms
doc
Information Need Rankingmatch
Information Need
query
Classic IR Models - Basic Concepts
The importance of the index terms is represented by weights associated to them
Let t be the number of index terms in the system K= {k1, k2, k3,... kt} set of all index terms ki be an index term
d be a document dj be a document wij is a weight associated with (ki,dj) wij = 0 indicates that term does not belong to docwij 0 indicates that term does not belong to doc vec(dj) = (w1j, w2j, , wtj) is a weighted vector
associated with the document dj gi(vec(dj)) = wij is a function which returns the weight
associated with pair (ki,dj)
The Boolean Model
Simple model based on set theory Only AND, OR and NOT are usedy , Queries specified as boolean expressions
precise semantics neat formalism q = ka (kb kc)
T ith t b t Th {0 1} Terms are either present or absent. Thus, wij {0,1} Consider
q = k (k k ) q = ka (kb kc) vec(qdnf) = (1,1,1) (1,1,0) (1,0,0) vec(qcc) = (1,1,0) is a conjunctive componentvec(qcc) (1,1,0) is a conjunctive component
The Boolean Model
k (k k ) (1 1 0)Ka Kb
q = ka (kb kc)(1,1,1)
(1,0,0)(1,1,0)
sim(q,dj) = 1 if vec(qcc) | Kc
j(vec(qcc) vec(qdnf)) (ki, gi(vec(dj)) = gi(vec(qcc)))
0 otherwise0 otherwise
Drawbacks of the Boolean Model
Retrieval based on binary decision criteria with no notion of partial matching
No ranking of the documents is provided (absence of a grading scale)Information need has to be translated into a Boolean Information need has to be translated into a Boolean expression which most users find awkward
The Boolean queries formulated by the users are most often q ytoo simplistic
As a consequence, the Boolean model frequently returns ith t f t d t i teither too few or too many documents in response to a user
query
The Vector Model
Use of binary weights is too limitingNon binary weights provide consideration for Non-binary weights provide consideration for partial matches
These term weights are used to compute a degree of similarity between a query and each document
Ranked set of documents provides for better matching
The Vector Model Define: Define:
wij > 0 whenever ki djw >= 0 associated with the pair (k q) wiq >= 0 associated with the pair (ki,q)
vec(dj) = (w1j, w2j, ..., wtj)vec(q) = (w w w )vec(q) = (w1q, w2q, ..., wtq)
In this space queries and documents are In this space, queries and documents are represented as weighted vectors
The Vector Modelj
dj
i
q
Sim(q,dj) = cos()= [vec(dj) vec(q)] / |dj| * |q|= [ wij * wiq] / |dj| * |q|
Si 0 d 0 0 i ( d ) 1
i
Since wij > 0 and wiq > 0, 0
The Vector Model
Sim(q,dj) = [ wij * wiq] / |dj| * |q| How to compute the weights wij and wi ? How to compute the weights wij and wiq ? A good weight must take into account two
effects:effects: quantification of intra-document contents
(similarity)(similarity) tf factor, the term frequency within a document
quantification of inter-documents separation (dissi- quantification of inter-documents separation (dissi-milarity) idf factor, the inverse document frequencyd acto , t e e se docu e t eque cy
wij = tf(i,j) * idf(i)
The Vector Model Let,
N be the total number of docs in the collection ni be the number of docs which contain ki freq(i,j) raw frequency of ki within dj
A normalized tf factor is given byf(i j) = freq(i j) / max (freq(l j)) f(i,j) = freq(i,j) / maxl(freq(l,j))
where the maximum is computed over all terms which occur within the document djj
The idf factor is computed as idf(i) = log (N/ni) the log is used to make the values of tf and idf
comparable. It can also be interpreted as the amount of information associated with the term kiinformation associated with the term ki.
The Vector Model The best term-weighting schemes use weights which are give
by w = f(i j) * log(N/n ) wij = f(i,j) * log(N/ni)
the strategy is called a tf-idf weighting scheme For the query term weights, a suggestion isFor the query term weights, a suggestion is
wiq = (0.5 + [0.5 * freq(i,q) / max(freq(l,q)]) * log(N/ni) The vector model with tf-idf weights is a good ranking
strategy with general collections The vector model is usually as good as the known ranking
alternatives It is also simple and fast to computealternatives. It is also simple and fast to compute.
The Vector Model
Advantages: term-weighting improves quality of the answer setg g partial matching allows retrieval of docs that
approximate the query conditions cosine ranking formula sorts documents according
to degree of similarity to the query
Disadvantages: assumes independence of index terms (??); not p ( );
clear that this is bad though
The Vector Model: Example I
d7k1
k2
d1
d2
d3d4 d5
d6d7
d1
k3
k1 k2 k3 q djd1 1 0 1 2d2 1 0 0 1d3 0 1 1 2d4 1 0 0 1d5 1 1 1 3d6 1 1 0 2d7 0 1 0 1
q 1 1 1
The Vector Model: Example II
d7k1
k2
d1
d2
d3d4 d5
d6d7
d1
k3
k1 k2 k3 q djd1 1 0 1 4d2 1 0 0 1d2 1 0 0 1d3 0 1 1 5d4 1 0 0 1d5 1 1 1 6d5 1 1 1 6d6 1 1 0 3d7 0 1 0 2
q 1 2 3
The Vector Model: Example III
d7k1
k2
d1
d2
d3d4 d5
d6d7
d1
k3
k1 k2 k3 q djd1 2 0 1 5d2 1 0 0 1d2 1 0 0 1d3 0 1 3 11d4 2 0 0 2d5 1 2 4 17d5 1 2 4 17d6 1 2 0 5d7 0 5 0 10
q 1 2 3