CSCI 5832 Natural Language Processing Lecture 23 Jim Martin 4 24 07 CSCI 5832 Spring 2006 1 Today 4 17 Finish Lexical Semantics Wrap up Information Extraction 4 24 07 CSCI 5832 Spring 2006 2 1 Inside Words Thematic roles more on the stuff that goes on inside verbs 4 24 07 CSCI 5832 Spring 2006 3 Inside Verbs Semantic generalizations over the specific roles that occur with specific verbs I e Takers givers eaters makers doers killers all have something in common er They re all the agents of the actions We can generalize or try to across other roles as well 4 24 07 CSCI 5832 Spring 2006 4 2 Thematic Roles 4 24 07 CSCI 5832 Spring 2006 5 Thematic Role Examples 4 24 07 CSCI 5832 Spring 2006 6 3 Why Thematic Roles It s not the case that every verb is unique and has to introduce unique labels for all of its roles thematic roles let us specify a fixed set of roles More importantly it permits us to distinguish surface level shallow semantics from deeper semantics 4 24 07 CSCI 5832 Spring 2006 7 Example From the WSJ He melted her reserve with a husky voiced paean to her eyes If we label the constituents He and reserve as the Melter and Melted then those labels lose any meaning they might have had literally If we make them Agent and Theme then we don t have the same problems 4 24 07 CSCI 5832 Spring 2006 8 4 Tasks Shallow semantic analysis is defined as Assigning the right labels to the arguments of verb in a sentence Aka Case role assignment Thematic role assignment 4 24 07 CSCI 5832 Spring 2006 9 Example Newswire text British forces agent believe target that Ali was killed in a recent air raid theme British forces believe that Ali theme was killed target in a recent air raid temporal 4 24 07 CSCI 5832 Spring 2006 10 5 Resources PropBank Annotate every verb in the Penn Treebank with its semantic arguments Use a fixed 25 or so set of role labels Arg0 Arg1 Every verb has a set of frames associated with it that indicate what its roles are So for Give we re told that Arg0 Giver 4 24 07 CSCI 5832 Spring 2006 11 Resources Propbank Since it s built on the treebank we have the trees and the parts of speech for all the words in each sentence Since it s a corpus we have the statistical coverage information we need for training machine learning systems 4 24 07 CSCI 5832 Spring 2006 12 6 Resources Propbank Since it s the WSJ it contains some fairly odd domain specific word uses that don t match our intuitions of the normal use of the words Similarly the word distribution is skewed by the genre from normal English whatever that means There s no unifying semantic theory behind the various frame files buy and sell are essentially unrelated 4 24 07 CSCI 5832 Spring 2006 13 Resources FrameNet Instead of annotating a corpus annotate domains of human knowledge a domain at a time called frames Then within a domain annotate lexical items from within that domain Develop a set of semantic roles called frame elements that are based on the domain and shared across the lexical items in the frame 4 24 07 CSCI 5832 Spring 2006 14 7 Cause Harm Frame 4 24 07 CSCI 5832 Spring 2006 15 Lexical Units 4 24 07 CSCI 5832 Spring 2006 16 8 FrameNet Frames and frame elements are entities in a hierarchy Cause Harm inherits from Transitive Action Corporal Punishment inherits from Cause Harm The victim FE in Cause Harm inherits from the patient FE of Transitive Action And the evaluee of the Corporal Punishment frame inherits from the victim of the Cause Harm frame 4 24 07 CSCI 5832 Spring 2006 17 FrameNet Framenet icsi berkeley edu 4 24 07 CSCI 5832 Spring 2006 18 9 Break Thursday we ll turn to discourse Chapter 20 Next week Stat MT Final quiz will be on May 1 4 24 07 CSCI 5832 Spring 2006 19 HLT Certificate You may be on your way to the Human Language Technology Certificate For typical CS students 5 courses CS NLP UI design AI Ling Syntax and Morphology Phonetics 4 24 07 CSCI 5832 Spring 2006 20 10 Information Extraction CHICAGO AP Citing high fuel prices United Airlines said Friday it has increased fares by 6 per round trip on flights to some cities also served by lower cost carriers American Airlines a unit AMR immediately matched the move spokesman Tim Wagner said United a unit of UAL said the increase took effect Thursday night and applies to most routes where it competes against discount carriers such as Chicago to Dallas and Atlanta and Denver to San Francisco Los Angeles and New York 4 24 07 CSCI 5832 Spring 2006 21 Information Extraction CHICAGO AP Citing high fuel prices United Airlines said Friday it has increased fares by 6 per round trip on flights to some cities also served by lower cost carriers American Airlines a unit AMR immediately matched the move spokesman Tim Wagner said United a unit of UAL said the increase took effect Thursday night and applies to most routes where it competes against discount carriers such as Chicago to Dallas and Atlanta and Denver to San Francisco Los Angeles and New York 4 24 07 CSCI 5832 Spring 2006 22 11 Named Entity Recognition Find the named entities and classify them by type Typical approach 4 24 07 Acquire training data Encode using IOB labeling Train a sequential supervised classifier Augment with pre and post processing using available list resources census data gazeteers etc CSCI 5832 Spring 2006 23 Information Extraction CHICAGO AP Citing high fuel prices United Airlines said Friday it has increased fares by 6 per round trip on flights to some cities also served by lower cost carriers American Airlines a unit AMR immediately matched the move spokesman Tim Wagner said United a unit of UAL said the increase took effect Thursday night and applies to most routes where it competes against discount carriers such as Chicago to Dallas and Atlanta and Denver to San Francisco Los Angeles and New York 4 24 07 CSCI 5832 Spring 2006 24 12 Temporal and Numerical Expressions Temporals Find all the temporal expressions Normalize them based on some reference point Numerical Expressions Find all the expressions Classify by type Normalize 4 24 07 CSCI 5832 Spring 2006 25 Information Extraction CHICAGO AP Citing high fuel prices United Airlines said Friday it has increased fares by 6 per round trip on flights to some cities also served by lower cost carriers American Airlines a unit AMR immediately matched the move spokesman Tim Wagner said United a unit of UAL said the increase took effect Thursday night and applies to most routes where it competes against discount carriers such as Chicago to
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