A Domain Based Approach to Information Retrieval in Digital Libraries - Rotella, Ferilli, Leuzzi

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The current abundance of electronic documents requires automatic techniques that support the users in understanding their content and extracting useful information. To this aim, improving the retrieval performance must necessarily go beyond simple lexical interpretation of the user queries, and pass through an understanding of their semantic content and aims. It goes without saying that any digital library would take enormous advantage from the availability of effective Information Retrieval techniques to provide to their users. This paper proposes an approach to Information Retrieval based on a correspondence of the domain of discourse between the query and the documents in the repository. Such an association is based on standard general-purpose linguistic resources (WordNet and WordNet Domains) and on a novel similarity assessment technique. Although the work is at a preliminary stage, interesting initial results suggest to go on extending and improving the approach.

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A Domain Based Approach to Information Retrieval in Digital Libraries - Rotella, Ferilli, Leuzzi

  1. 1. Università degli studi di Bari “Aldo Moro” Dipartimento di Informatica A Domain Based Approach to Information Retrieval in Digital Libraries F. Rotella , S. Ferilli, F. Leuzzi [email_address] , {fabio.leuzzi, rotella.fulvio}@gmail.com 8th Italian Research Conference on Digital Libraries Bari, Italy, February 9-10, 2012 L.A.C.A.M. http://lacam.di.uniba.it:8000
  2. 2. Overview <ul><li>Introduction & Objectives
  3. 3. Keyword Extraction
  4. 4. Word Sense Disambiguation
  5. 5. Synset Clustering
  6. 6. A Multistrategy Similarity Measure
  7. 7. Document Partitioning
  8. 8. User Query Processing
  9. 9. A Preliminary Evaluation
  10. 10. Conclusions & Future Works </li></ul>A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi
  11. 11. Some repositories leave the responsibility of quality to the authors. + Anybody can produce and distribute documents. = Possible low average quality of the repository contents. Users are often overwhelmed by documents that only apparently are suitable for satisfying their information needs . Introduction A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi
  12. 12. Introduction <ul><li>Possible way out: Information Retrieval systems
  13. 13. Numerical/statistical manipulation of (key)words has been widely explored in the literature </li><ul><li>Still unable to fully solve the problem </li></ul><li>Achieving better retrieval performance requires to go beyond simple lexical interpretation of the user queries </li><ul><li>Pass through an understanding of their semantic content and aims </li></ul><li>Ontological taxonomy </li><ul><li>WordNet
  14. 14. WordNet Domains </li></ul></ul>A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi
  15. 15. Objectives Improving fruition of a DL <ul><li>Use of advanced techniques for document retrieval
  16. 16. Try to overcome the ambiguity of natural language
  17. 17. Inspired by the typical behavior of humans: </li><ul><li>take into account the possible meanings of words
  18. 18. select the most appropriate one according to the context of the discourse </li></ul></ul>A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi
  19. 19. Keyword Extraction <ul><li>Each document in the digital library is progressively split into paragraphs, sentences, and single words </li><ul><li>Integrated in the DOMINUS framework </li></ul><li>Obtained the syntactic structure of sentences, and the lemmas </li><ul><li>Integrated in the Stanford Parser </li></ul><li>Classical VSM </li><ul><li>TF*IDF weighting </li></ul><li>Two filters: </li><ul><li>Only nouns considered </li><ul><li>The representation of adverbs, verbs and adjectives in WordNet is different </li></ul><li>Only the top 10% keywords for each document </li><ul><li>To be noise-tolerant
  20. 20. To limit the possibility of including non-discriminative and very general words in the representation of a document </li></ul></ul></ul>A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi
  21. 21. Word Sense Disambiguation Domain Driven One Domain per Discourse assumption: many uses of a word in a coherent portion of text tend to share the same domain. A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi Prevalent domain individuation Extraction of all synsets for each term Extraction of all domains for each synset Choice of prevalent domain synset
  22. 22. Synset Clustering Pairwise complete link agglomerative strategy A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi <ul><li>Each synset generates a singleton cluster
  23. 23. For each pair of clusters </li><ul><li>If the complete link property holds </li><ul><li>Merge the involved clusters </li></ul></ul></ul>
  24. 24. A Multistrategy Similarity Measure Cooperating Techniques for Extracting Conceptual Taxonomies from Text - S. Ferilli, F. Leuzzi, F. Rotella 3 components are summed and normalized, in ]0,1[ <ul><li>depth (ancestors)
  25. 25. breadth (direct neighbors)
  26. 26. breadth (inverse neighbors) </li></ul>WordNet relationship are considered
  27. 27. A Multistrategy Similarity Measure Cosidered Relationship member meronimy : the latter synset is a member meronym of the former; substance meronimy : the latter synset is a substance meronym of the former; part meronimy : the latter synset is a part meronym of the former; similarity : the latter synset is similar in meaning to the former; antonym : specifies antonymous word; attribute : defines the attribute relation between noun and adjective synset pairs in which the adjective is a value of the noun; additional information : additional information about the first word can be obtained by seeing the second word; part of speech based : specifies two different relations based on the parts of speech involved; participle : the adjective first word is a participle of the verb second word; hyperonymy : the latter synset is a hypernym of the former. A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi
  28. 28. Document Partitioning <ul><li>SynsetWord structure: </li><ul><li>Original word
  29. 29. TF*IDF weight
  30. 30. Synset </li></ul><li>The Pairwise Clustering step returned a set of synset clusters
  31. 31. For each document in the collection </li><ul><li>Each of its SynsetWord votes with its TF*IDF weight
  32. 32. The first three clusters are chosen from the ranked list </li><ul><li>They represent the intensional description of the document </li></ul></ul></ul>A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi
  33. 33. Users Query Elaboration Overview <ul><li>Same grammatical preprocessing as in the previous phase
  34. 34. Query usually very short </li><ul><li>No keyword extraction: all nouns retained for the next operations
  35. 35. WSD Domain Driven unreliable </li><ul><li>For each word, all corresponding synsets in WordNet are kept
  36. 36. A single lexical query yields many semantic queries </li><ul><li>All possible combinations of synsets </li></ul></ul></ul></ul>A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi
  37. 37. Users Query Elaboration A Brute Force WSD <ul><li>For each combination: </li></ul><ul><ul><li>a similarity evaluated against each cluster that has at least one associated document
  38. 38. using the same similarity function as for clustering </li></ul></ul><ul><li>Twofold objective : </li></ul><ul><ul><li>finding the combination of synsets that represents the best word sense disambiguation
  39. 39. obtaining the most similar cluster to the involved words </li></ul></ul>A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi
  40. 40. Users Query Elaboration Query Results The best combination is used to obtain the list of clusters ranked by descending relevance, that can be used as an answer to the user search . The results are then displayed to the user, in particular are displayed the first n sets of document such that n is the minimum value that shows at least 10 results. A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi
  41. 41. A Preliminary Evaluation The Quality of Clusters A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi 86 documents, 4 topics: 27 general science and physics; 21 music; 15 politics; 23 religion. Query: Reincarnation and eternal life Best combination: <ul><li>synset: 106191212; lemmas: reincarnation ; gloss: the Hindu or Buddhist doctrine that a person may be reborn successively into one of five classes of living beings (god or human or animal or hungry ghost or denizen of Hell) depending on the person’s own actions;
  42. 42. synset: 100006269; lemmas: life ; gloss: living things collectively. </li></ul>Most similar cluster: <ul><li>synset: 106191212; lemmas: reincarnation ; gloss: the Hindu or Buddhist doctrine that a person may be reborn successively into one of five classes of living beings (god or human or animal or hungry ghost or denizen of Hell) depending on the person’s own actions;
  43. 43. synset: 105943300; lemmas: doctrine, philosophical system, philosophy and school of thought; gloss: a belief (or system of beliefs) accepted as authoritative by some group or school;
  44. 44. synset: 105941423; lemmas: belief ; gloss: any cognitive content held as true. </li></ul>
  45. 45. Query: Ornaments and melodies Best combination: <ul><li>synset: 103169390; lemmas: decoration , ornament and ornamentation; gloss: something used to beautify;
  46. 46. synset: 107028373; lemmas: air, line, melodic line, melodic phrase, melody , strain and tune; gloss: a succession of notes forming a distinctive sequence. </li></ul>Most similar cluster: <ul><li>synset: 107025900; lemmas: classical, classical music and serious music; gloss: traditional genre of music conforming to an established form and appealing to critical interest and developed musical taste;
  47. 47. synset: 107033753; lemmas: mass ; gloss: a musical setting for a Mass;
  48. 48. synset: 107026352; lemmas: opera ; gloss: a drama set to music, consists of singing with orchestral accompaniment and an orchestral overture and interludes;
  49. 49. synset: 107071942; lemmas: genre, music genre , musical genre and musical style; gloss: an expressive style of music;
  50. 50. synset: 107064715; lemmas: rock , rock ’n’ roll, rock and roll, rock music, rock’n’roll and rock-and-roll; gloss: a genre of popular music originating in the 1950s, a blend of black rhythm-and-blues with white country-and-western. </li></ul>A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi A Preliminary Evaluation The Quality of Clusters
  51. 51. A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi # Query Outcomes Precision Recall 1 Ornaments and melodies [1 to 9] music [10 to 11] religion 0.82 (1.0) 0.43 (9/21) 2 Reincarnation and eternal life [1 to 9] religion [10] science 0.9 (1.0) 0.39 (9/23) 3 Traditions and folks [1 to 4] music [5 to 6] religion [7 to 10] music 0.8 (1.0) 0.38 (8/21) 4 Limits of theory of relativity [1 to 2] science [3] politics [4 to 5] religion [6 to 15] science 0.8 0.44 (12/27) 5 Capitalism vs communism [1 to 3] politics [4] science [5 to 6] religion [7 to 11] politics [12] science [13] music 0.61 (0.77) 0.53 (8/15) 6 Markets and new economy [1] politics [2] music [3] science [4 to 8] politics [9 to 10] religion 0.6 (0.7) 0.4 (6/15) 7 Relationship between democracy and parliament [1 to 3] politics [4] science [5 to 6] politics [7 to 10] religion 0.5 (0.6) 0.33 (5/15) A Preliminary Evaluation Synthesis of Outcomes
  52. 52. Conclusions <ul><li>Proposed an approach to extract information from digital libraries </li><ul><li>Go beyond simple lexical matching, toward the semantic content underlying queries </li></ul><li>The approach consists of: </li><ul><li>An off-line preprocessing on the entire corpus </li><ul><li>Find sets of synset as intensional descriptions for the documents </li></ul><li>An on-line phase on the queries </li><ul><li>Find the most suitable sense, evaluating all possible combinations of synset against each intensional descriptions of the documents </li><ul><li>In order to propose as result the most relevant ones </li></ul></ul></ul><li>Preliminary experiments show that this approach can be viable . </li></ul>A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi
  53. 53. Future Works <ul><li>Substitution of the ODD assumption with a more elaborated strategy for WSD
  54. 54. Avoiding the pre-processing step </li><ul><li>To handle cases when new documents are progressively included in the collection </li></ul><li>Including adverbs, verbs and adjectives </li><ul><li>To improve the quality of the semantic representatives of the document s
  55. 55. To explore other approaches to choose better intensional descriptions of each document </li></ul></ul>A Domain Based Approach to Information Retrieval in Digital Libraries - F. Rotella, S. Ferilli, F. Leuzzi

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