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MTech Seminar Presentation [IIT-Bombay]

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Seminar presentation made by me for the topic of 'Resources for Sentiment Analysis' at IIT Bombay. Includes a set of bonus slides for additional information which was not actually presented.

Seminar presentation made by me for the topic of 'Resources for Sentiment Analysis' at IIT Bombay. Includes a set of bonus slides for additional information which was not actually presented.

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  • 1. Resources for Sentiment Analysis Seminar Presentation Sagar Ahire 133050073 IIT Bombay 02 May, 2014 Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 1 / 48
  • 2. Roadmap 1 Introduction 2 Sentiwordnet 3 SO-CAL 4 Wordnet-Affect 5 Indian-Language Sentiwordnets 6 Conclusions Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 2 / 48
  • 3. Introduction Roadmap: We Are Here 1 Introduction 2 Sentiwordnet 3 SO-CAL 4 Wordnet-Affect 5 Indian-Language Sentiwordnets 6 Conclusions Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 3 / 48
  • 4. Introduction Overview Overview An overview of today’s presentation: This presentation covers lexical resources for sentiment analysis. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 4 / 48
  • 5. Introduction Overview Overview An overview of today’s presentation: This presentation covers lexical resources for sentiment analysis. Four resources are covered, each using a different approach for representation and creation: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 4 / 48
  • 6. Introduction Overview Overview An overview of today’s presentation: This presentation covers lexical resources for sentiment analysis. Four resources are covered, each using a different approach for representation and creation: Sentiwordnet, created automatically, with 3 graded scores per synset Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 4 / 48
  • 7. Introduction Overview Overview An overview of today’s presentation: This presentation covers lexical resources for sentiment analysis. Four resources are covered, each using a different approach for representation and creation: Sentiwordnet, created automatically, with 3 graded scores per synset SO-CAL, created manually, with a graded score per word Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 4 / 48
  • 8. Introduction Overview Overview An overview of today’s presentation: This presentation covers lexical resources for sentiment analysis. Four resources are covered, each using a different approach for representation and creation: Sentiwordnet, created automatically, with 3 graded scores per synset SO-CAL, created manually, with a graded score per word Wordnet-Affect, created semi-automatically, with affect information for each synset Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 4 / 48
  • 9. Introduction Overview Overview An overview of today’s presentation: This presentation covers lexical resources for sentiment analysis. Four resources are covered, each using a different approach for representation and creation: Sentiwordnet, created automatically, with 3 graded scores per synset SO-CAL, created manually, with a graded score per word Wordnet-Affect, created semi-automatically, with affect information for each synset Indian-Language Sentiwordnet, created by projecting the English Sentiwordnet Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 4 / 48
  • 10. Introduction Sentiment Analysis Sentiment Analysis Sentiment Analysis: Determining the opinion expressed in a text Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 5 / 48
  • 11. Introduction Sentiment Analysis Sentiment Analysis Sentiment Analysis: Determining the opinion expressed in a text Approaches: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 5 / 48
  • 12. Introduction Sentiment Analysis Sentiment Analysis Sentiment Analysis: Determining the opinion expressed in a text Approaches: Classifier-based Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 5 / 48
  • 13. Introduction Sentiment Analysis Sentiment Analysis Sentiment Analysis: Determining the opinion expressed in a text Approaches: Classifier-based Lexicon-based Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 5 / 48
  • 14. Introduction Sentiment Analysis Why Lexicon-based Approach? The classifier-based approach has the following drawbacks: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 6 / 48
  • 15. Introduction Sentiment Analysis Why Lexicon-based Approach? The classifier-based approach has the following drawbacks: Domain Specificity (Example: Movie reviews mentioning ‘writer’, ‘plot’, etc.) [Bro01] Lack of Context (Example: ‘good’ vs ‘not good’ vs ‘not very good’) Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 6 / 48
  • 16. Introduction Sentiment Analysis Why Lexicon-based Approach? The classifier-based approach has the following drawbacks: Domain Specificity (Example: Movie reviews mentioning ‘writer’, ‘plot’, etc.) [Bro01] Lack of Context (Example: ‘good’ vs ‘not good’ vs ‘not very good’) The lexicon-based approach aims at solving these problems. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 6 / 48
  • 17. Introduction Sentiment Lexicons Sentiment Lexicons A sentiment lexicon is a sentiment database for language units of the form (lexical unit, sentiment). Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 7 / 48
  • 18. Introduction Sentiment Lexicons Sentiment Lexicons A sentiment lexicon is a sentiment database for language units of the form (lexical unit, sentiment). Choices for lexical unit: Word Word sense Phrase, etc. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 7 / 48
  • 19. Introduction Sentiment Lexicons Sentiment Lexicons A sentiment lexicon is a sentiment database for language units of the form (lexical unit, sentiment). Choices for lexical unit: Word Word sense Phrase, etc. Choices for sentiment: Fixed categorization into ‘positive’ and ‘negative’ Graded sets like ‘strongly positive’, ‘mildly positive’, ‘neutral’, ‘mildly negative’, ‘strongly negative’ Score in an interval like [0, 1] or [−1, +1] Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 7 / 48
  • 20. Introduction Sentiment Lexicons Approaches for Creation Manual Automatic Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 8 / 48
  • 21. Sentiwordnet Roadmap: We Are Here 1 Introduction 2 Sentiwordnet 3 SO-CAL 4 Wordnet-Affect 5 Indian-Language Sentiwordnets 6 Conclusions Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 9 / 48
  • 22. Sentiwordnet Introduction to Sentiwordnet Sentiwordnet [ES06] is an automatically generated sentiment lexicon made using Wordnet. Its salient features are: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 10 / 48
  • 23. Sentiwordnet Introduction to Sentiwordnet Sentiwordnet [ES06] is an automatically generated sentiment lexicon made using Wordnet. Its salient features are: High coverage Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 10 / 48
  • 24. Sentiwordnet Introduction to Sentiwordnet Sentiwordnet [ES06] is an automatically generated sentiment lexicon made using Wordnet. Its salient features are: High coverage Support for graded sentiment labels Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 10 / 48
  • 25. Sentiwordnet Introduction to Sentiwordnet Sentiwordnet [ES06] is an automatically generated sentiment lexicon made using Wordnet. Its salient features are: High coverage Support for graded sentiment labels Support for both sentiment classification and subjectivity detection Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 10 / 48
  • 26. Sentiwordnet Structure Structure of Sentiwordnet Sentiwordnet = Wordnet + Sentiment Information. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 11 / 48
  • 27. Sentiwordnet Structure Structure of Sentiwordnet Sentiwordnet = Wordnet + Sentiment Information. Each synset s is given three sentiment scores: Positive score Pos(s) Negative score Neg(s) Objective score Obj(s) Pos(s) + Neg(s) + Obj(s) = 1 Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 11 / 48
  • 28. Sentiwordnet Structure Structure of Sentiwordnet Sentiwordnet = Wordnet + Sentiment Information. Each synset s is given three sentiment scores: Positive score Pos(s) Negative score Neg(s) Objective score Obj(s) Pos(s) + Neg(s) + Obj(s) = 1 Example Synset beautifula: Pos = 0.75, Neg = 0.00, Obj = 0.25 a URL: http://sentiwordnet.isti.cnr.it/search.php?q=beautiful Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 11 / 48
  • 29. Sentiwordnet Creation Creation Steps The top-level steps in the algorithm to create Sentiwordnet are as follows: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 12 / 48
  • 30. Sentiwordnet Creation Creation Steps The top-level steps in the algorithm to create Sentiwordnet are as follows: 1 Selection of seed set Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 12 / 48
  • 31. Sentiwordnet Creation Creation Steps The top-level steps in the algorithm to create Sentiwordnet are as follows: 1 Selection of seed set 2 Expansion using Wordnet’s semantic relations Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 12 / 48
  • 32. Sentiwordnet Creation Creation Steps The top-level steps in the algorithm to create Sentiwordnet are as follows: 1 Selection of seed set 2 Expansion using Wordnet’s semantic relations 3 Training of a team of ternary classifiers Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 12 / 48
  • 33. Sentiwordnet Creation Creation Steps The top-level steps in the algorithm to create Sentiwordnet are as follows: 1 Selection of seed set 2 Expansion using Wordnet’s semantic relations 3 Training of a team of ternary classifiers 4 Classification of each Wordnet synset using the classifiers Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 12 / 48
  • 34. SO-CAL Roadmap: We Are Here 1 Introduction 2 Sentiwordnet 3 SO-CAL 4 Wordnet-Affect 5 Indian-Language Sentiwordnets 6 Conclusions Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 13 / 48
  • 35. SO-CAL Introduction to SO-CAL SO-CAL is a system that uses a manually-constructed lexicon. Its salient features are: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 14 / 48
  • 36. SO-CAL Introduction to SO-CAL SO-CAL is a system that uses a manually-constructed lexicon. Its salient features are: Highly detailed lexicon Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 14 / 48
  • 37. SO-CAL Introduction to SO-CAL SO-CAL is a system that uses a manually-constructed lexicon. Its salient features are: Highly detailed lexicon Graded sentiment label Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 14 / 48
  • 38. SO-CAL Introduction to SO-CAL SO-CAL is a system that uses a manually-constructed lexicon. Its salient features are: Highly detailed lexicon Graded sentiment label Low coverage, but high accuracy Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 14 / 48
  • 39. SO-CAL Structure Features Used SO-CAL classifies words into various features and treats each feature differently in the lexicon. They are: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 15 / 48
  • 40. SO-CAL Structure Features Used SO-CAL classifies words into various features and treats each feature differently in the lexicon. They are: Adjectives Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 15 / 48
  • 41. SO-CAL Structure Features Used SO-CAL classifies words into various features and treats each feature differently in the lexicon. They are: Adjectives Nouns, Verbs, Adverbs and Multiwords Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 15 / 48
  • 42. SO-CAL Structure Features Used SO-CAL classifies words into various features and treats each feature differently in the lexicon. They are: Adjectives Nouns, Verbs, Adverbs and Multiwords Intensifiers and Downtoners Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 15 / 48
  • 43. SO-CAL Structure Features Used SO-CAL classifies words into various features and treats each feature differently in the lexicon. They are: Adjectives Nouns, Verbs, Adverbs and Multiwords Intensifiers and Downtoners Negation Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 15 / 48
  • 44. SO-CAL Structure Features Used SO-CAL classifies words into various features and treats each feature differently in the lexicon. They are: Adjectives Nouns, Verbs, Adverbs and Multiwords Intensifiers and Downtoners Negation Irrealis Blocking Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 15 / 48
  • 45. SO-CAL Structure Structure of SO-CAL Sentiment scoring: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 16 / 48
  • 46. SO-CAL Structure Structure of SO-CAL Sentiment scoring: Words are scored in [−5, +5] Intensifiers and negation further act upon these scores Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 16 / 48
  • 47. SO-CAL Structure Structure of SO-CAL Sentiment scoring: Words are scored in [−5, +5] Intensifiers and negation further act upon these scores Examples good: +3 monstrosity: −5 masterpiece: +5 Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 16 / 48
  • 48. Wordnet-Affect Roadmap: We Are Here 1 Introduction 2 Sentiwordnet 3 SO-CAL 4 Wordnet-Affect 5 Indian-Language Sentiwordnets 6 Conclusions Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 17 / 48
  • 49. Wordnet-Affect Introduction to Wordnet-Affect Wordnet-Affect [SV04] is a semi-automatically generated sentiment lexicon made using Wordnet. It associates affective information with each synset. Its salient features are: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 18 / 48
  • 50. Wordnet-Affect Introduction to Wordnet-Affect Wordnet-Affect [SV04] is a semi-automatically generated sentiment lexicon made using Wordnet. It associates affective information with each synset. Its salient features are: Highly detailed Ability to handle sentiment differently depending on emotion Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 18 / 48
  • 51. Wordnet-Affect Structure Structure of Wordnet-Affect Wordnet-Affect = Wordnet + Affect Information. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 19 / 48
  • 52. Wordnet-Affect Structure Structure of Wordnet-Affect Wordnet-Affect = Wordnet + Affect Information. Affect is represented using the following: An a-label which represents the emotion, The valency which indicates the sentiment. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 19 / 48
  • 53. Wordnet-Affect Structure Structure of Wordnet-Affect The a-label is a tree of emotions starting at a root node with each leaf node corresponding to a synset. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 20 / 48
  • 54. Wordnet-Affect Structure Structure of Wordnet-Affect The a-label is a tree of emotions starting at a root node with each leaf node corresponding to a synset. The valency can be any of positive, negative, neutral or ambiguous. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 20 / 48
  • 55. Wordnet-Affect Structure root mental-state cognitive-state affective-state mood emotion positive-emotion joy elation love worship negative-emotion sadness melancholy shame embarrassment . . . . . . physical-state . . . Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 21 / 48
  • 56. Wordnet-Affect Creation Creation Steps Wordnet-Affect was created using the following steps: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 22 / 48
  • 57. Wordnet-Affect Creation Creation Steps Wordnet-Affect was created using the following steps: Manual creation of initial resource Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 22 / 48
  • 58. Wordnet-Affect Creation Creation Steps Wordnet-Affect was created using the following steps: Manual creation of initial resource Automatic expansion using Wordnet relations Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 22 / 48
  • 59. Indian-Language Sentiwordnets Roadmap: We Are Here 1 Introduction 2 Sentiwordnet 3 SO-CAL 4 Wordnet-Affect 5 Indian-Language Sentiwordnets 6 Conclusions Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 23 / 48
  • 60. Indian-Language Sentiwordnets Introduction to Indian-Language Sentiwordnets Indian-language Sentiwordnets can be created using Wordnet projection [JRB10]. This approach has the following salient features: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 24 / 48
  • 61. Indian-Language Sentiwordnets Introduction to Indian-Language Sentiwordnets Indian-language Sentiwordnets can be created using Wordnet projection [JRB10]. This approach has the following salient features: Easy to create once backing resources are available No reduplication of effort Use of tried-and-tested representations Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 24 / 48
  • 62. Indian-Language Sentiwordnets Creation Creation Steps The process of projecting a Sentiwordnet has the following steps: Fetch a synset from the English Sentiwordnet. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 25 / 48
  • 63. Indian-Language Sentiwordnets Creation Creation Steps The process of projecting a Sentiwordnet has the following steps: Fetch a synset from the English Sentiwordnet. Find the corresponding Hindi synset using Indowordnet. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 25 / 48
  • 64. Indian-Language Sentiwordnets Creation Creation Steps The process of projecting a Sentiwordnet has the following steps: Fetch a synset from the English Sentiwordnet. Find the corresponding Hindi synset using Indowordnet. Assign sentiment scores from English synset to Hindi synset. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 25 / 48
  • 65. Conclusions Roadmap: We Are Here 1 Introduction 2 Sentiwordnet 3 SO-CAL 4 Wordnet-Affect 5 Indian-Language Sentiwordnets 6 Conclusions Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 26 / 48
  • 66. Conclusions A Comparison of the Resources Criterion SWN SO-CAL WN-Affect IL-SWN Sentiment 3 x [0, 1] [−5, +5] Affect 3 x [0, 1] Lexical Unit Synset Word Synset Synset Backing Resource Wordnet None Wordnet SWN + In- dowordnet Creation Automatic Manual Automatic Projection No of Entries 117,000 5,000 900 16,000 Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 27 / 48
  • 67. Conclusions Concluding Remarks To conclude, there are three choices in making a sentiment lexicon: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 28 / 48
  • 68. Conclusions Concluding Remarks To conclude, there are three choices in making a sentiment lexicon: Creation Approach: Manual, Automatic, Semi-Automatic or Projection Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 28 / 48
  • 69. Conclusions Concluding Remarks To conclude, there are three choices in making a sentiment lexicon: Creation Approach: Manual, Automatic, Semi-Automatic or Projection Lexical Unit: Word, Synset or Higher Representations Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 28 / 48
  • 70. Conclusions Concluding Remarks To conclude, there are three choices in making a sentiment lexicon: Creation Approach: Manual, Automatic, Semi-Automatic or Projection Lexical Unit: Word, Synset or Higher Representations Sentiment: Labels, Graded Scores or Affect Information Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 28 / 48
  • 71. Conclusions Concluding Remarks: Creation Approach Manual Approach Automatic Approach High annotation accuracy Low annotation accuracy High time investment Low time investment More details supported Less details supported Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 29 / 48
  • 72. Conclusions Concluding Remarks: Lexical Unit Word Synset Unreliable for polysemous words Reliable for polysemous words No pre-processing required Requires WSD Projection is comparatively difficult Projection is comparatively easier Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 30 / 48
  • 73. Conclusions Concluding Remarks: Sentiment Graded scores have been shown to be better than mere labels in general. Moreover, a graded score resource can always be converted to a label-based resource. Affect information can help in specialized circumstances. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 31 / 48
  • 74. Conclusions Future Work Possible directions in the future: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 32 / 48
  • 75. Conclusions Future Work Possible directions in the future: Automatic resources for higher-level lexical units like phrases, trees, etc. Manual resources for synsets Manual lexicons for Indian languages Techniques for building dynamic resources to incorporate ‘netspeak’ and other slang Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 32 / 48
  • 76. Conclusions References I Julian Brooke, A semantic approach to automatic text sentiment analysis, M.A. thesis, Stanford University, 2001. Andrea Esuli and Fabrizio Sebastiani, SentiWordNet: A publicly available lexical resource for opinion mining, Proceedings of the 5th Conference on Language Resources and Evaluation (LREC-06), 2006, pp. 417–422. Andrea Esuli, Automatic generation of lexical resources for opinion mining: Models, algorithms and applications, Ph.D. thesis, Universita di Pisa, 2008. Christiane Fellbaum, Wordnet: An electronic lexical database, A Bradford Book, 1998. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 33 / 48
  • 77. Conclusions References II Vasileios Hatzivassiloglou and Kathleen R. McKeown, Predicting the semantic orientation of adjectives, Proceedings of the 35th Annual Meeting of the Association for Computational Linguistics and Eighth Conference of the European Chapter of the Association for Computational Linguistics, Association for Computational Linguistics, 1997, pp. 174–181. Aditya Joshi, Balamurali A R, and Pushpak Bhattacharyya, A fall-back strategy for sentiment analysis in hindi: a case study, Proceedings of ICON 2010: 8th International Conference on Natural Language Processing, Macmillan Publishers, India, 2010. Jaap Kamps, Maarten Marx, Robert J. Mokken, and Maarten de Rijke, Using wordnet to measure semantic orientations of adjectives, Proceedings of LREC-04, 4th International Conference on Language Resources and Evaluation, 2004, pp. 1115–1118. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 34 / 48
  • 78. Conclusions References III Ellen Riloff and Janyce Wiebe, Learning extraction patterns for subjective expressions, Proceedings of the 2003 Conference on Empirical Methods in Natural Language Processing, Association for Computational Linguistics, 2003, pp. 105–112. Carlo Strapparava and Alessandro Valitutti, WordNet-Affect: an affective extension of WordNet, Proceedings of the 4th International Conference on Language Resources and Evaluation (LREC-04), 2004, pp. 1083–1086. Peter D. Turney and Michael L. Littman, Measuring praise and criticism: Inference of semantic orientation from association, ACM Transactions on Information Systems 21 (2003), no. 4, 315–346. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 35 / 48
  • 79. Additional Slides Wordnet Wordnet Wordnet [Fel98] is a lexical database organized by word sense. The fundamental unit of storage is called a synset. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 36 / 48
  • 80. Additional Slides Wordnet Wordnet Wordnet [Fel98] is a lexical database organized by word sense. The fundamental unit of storage is called a synset. An Example Synset brilliant, superba: of surpassing excellence “a brilliant performance”; “a superb actor” a URL: http://wordnetweb.princeton.edu/perl/webwn?s=brilliant Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 36 / 48
  • 81. Additional Slides Wordnet Semantic Relations in Wordnet Wordnet synsets are linked to each other by relations called semantic relations. Some of them are: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 37 / 48
  • 82. Additional Slides Wordnet Semantic Relations in Wordnet Wordnet synsets are linked to each other by relations called semantic relations. Some of them are: Antonymy Meronymy Hypernymy Hyponymy Similar to, etc. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 37 / 48
  • 83. Additional Slides Wordnet Semantic Relations in Wordnet Wordnet synsets are linked to each other by relations called semantic relations. Some of them are: Antonymy Meronymy Hypernymy Hyponymy Similar to, etc. These relations are helpful in creating the training set for classifying synsets to create Sentiwordnet. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 37 / 48
  • 84. Additional Slides Background Sentiment Classification Initial work that automatically detected the sentiment of a word led to today’s modern lexicons. This included: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 38 / 48
  • 85. Additional Slides Background Sentiment Classification Initial work that automatically detected the sentiment of a word led to today’s modern lexicons. This included: Use of conjunction-separated adjectives [HM97] Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 38 / 48
  • 86. Additional Slides Background Sentiment Classification Initial work that automatically detected the sentiment of a word led to today’s modern lexicons. This included: Use of conjunction-separated adjectives [HM97] PMI-based Extraction using Web Queries [TL03] Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 38 / 48
  • 87. Additional Slides Background Sentiment Classification Initial work that automatically detected the sentiment of a word led to today’s modern lexicons. This included: Use of conjunction-separated adjectives [HM97] PMI-based Extraction using Web Queries [TL03] Graph Expansion using Wordnet [KMMdR04] Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 38 / 48
  • 88. Additional Slides Background Sentiment Classification Initial work that automatically detected the sentiment of a word led to today’s modern lexicons. This included: Use of conjunction-separated adjectives [HM97] PMI-based Extraction using Web Queries [TL03] Graph Expansion using Wordnet [KMMdR04] Classification using Wordnet Glosses [Esu08] Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 38 / 48
  • 89. Additional Slides Background Subjectivity Detection Work that identifies whether a term is indeed subjective is necessary to filter out objective words from sentiment classification. This includes: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 39 / 48
  • 90. Additional Slides Background Subjectivity Detection Work that identifies whether a term is indeed subjective is necessary to filter out objective words from sentiment classification. This includes: Adapting Wordnet Glosses to Subjectivity Detection [Esu08] Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 39 / 48
  • 91. Additional Slides Background Subjectivity Detection Work that identifies whether a term is indeed subjective is necessary to filter out objective words from sentiment classification. This includes: Adapting Wordnet Glosses to Subjectivity Detection [Esu08] Bootstrapping Subjective Expressions from a Corpus [RW03] Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 39 / 48
  • 92. Additional Slides Structure of SO-CAL Adjectives Adjectives were collected from a 500-document corpus and annotated with a sentiment score from −5 to +5. Examples good: +3 sleazy: −3 Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 40 / 48
  • 93. Additional Slides Structure of SO-CAL Nouns, Verbs, Adverbs, Multiwords This was extended to other parts of speech and multiword expressions, for a total of about 5,000 words. Examples monstrosity: −5 masterpiece: +5 inspire: +2 funny: +2 vs. act funny: −1 Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 41 / 48
  • 94. Additional Slides Structure of SO-CAL Intensifiers and Downtoners Intensifiers are words that increase sentiment intensity while downtoners are words that reduce sentiment intensity. For example extraordinarily and somewhat. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 42 / 48
  • 95. Additional Slides Structure of SO-CAL Intensifiers and Downtoners Intensifiers are words that increase sentiment intensity while downtoners are words that reduce sentiment intensity. For example extraordinarily and somewhat. Intensifiers and downtoners are modeled as percentage modifiers. Examples slightly: −50% extraordinarily: +50% Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 42 / 48
  • 96. Additional Slides Structure of SO-CAL Negation Negation is modeled as a numeric shift of value 4 towards the opposite sentiment. Examples good: +3 ⇒ not good: −1 atrocious: −5 ⇒ not atrocious: −1 Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 43 / 48
  • 97. Additional Slides Structure of SO-CAL Irrealis Blocking An irrealis marker is a word that indicates that the sentiment may not be reliable because the event hasn’t actually happened. For example, ‘would’, ‘expect’, ‘if’, quotation marks, etc. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 44 / 48
  • 98. Additional Slides Structure of SO-CAL Irrealis Blocking An irrealis marker is a word that indicates that the sentiment may not be reliable because the event hasn’t actually happened. For example, ‘would’, ‘expect’, ‘if’, quotation marks, etc. Sentences with irrealis markers are ignored for sentiment analysis. Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 44 / 48
  • 99. Additional Slides Sentiwordnet Creation Seed Set Two seed sets are created: Lp for positive synsets Ln for negative synsets Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 45 / 48
  • 100. Additional Slides Sentiwordnet Creation Seed Set Two seed sets are created: Lp for positive synsets Ln for negative synsets Each synset representation consists of: The terms The defninition The sample phrases Explicit indication of negation Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 45 / 48
  • 101. Additional Slides Sentiwordnet Creation Wordnet Expansion Relations of Wordnet used for expansion: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 46 / 48
  • 102. Additional Slides Sentiwordnet Creation Wordnet Expansion Relations of Wordnet used for expansion: Direct antonymy Similarity Derived from Pertains to Attribute Also see Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 46 / 48
  • 103. Additional Slides Sentiwordnet Creation Classifiers 8 classifiers were created differing in: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 47 / 48
  • 104. Additional Slides Sentiwordnet Creation Classifiers 8 classifiers were created differing in: No of iterations of expansion (0, 2, 4, 6) Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 47 / 48
  • 105. Additional Slides Sentiwordnet Creation Classifiers 8 classifiers were created differing in: No of iterations of expansion (0, 2, 4, 6) Learning algorithm (SVM, Rocchio) Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 47 / 48
  • 106. Additional Slides Sentiwordnet Creation Classifiers Each ternary classifier is a sum of 2 binary classifiers: Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 48 / 48
  • 107. Additional Slides Sentiwordnet Creation Classifiers Each ternary classifier is a sum of 2 binary classifiers: Positive vs. Not Positive Negative vs. Not Negative Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 48 / 48
  • 108. Additional Slides Sentiwordnet Creation Classifiers Each ternary classifier is a sum of 2 binary classifiers: Positive vs. Not Positive Negative vs. Not Negative The results are combined as: Positive Not Positive Negative Objective Negative Not Negative Positive Objective Sagar Ahire (IIT Bombay) Sentiment Resources 02 May, 2014 48 / 48