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Learn about file format, training examples generation, feature extraction, MaxEnt model training, decoding, and scoring for relation extraction. Understand methods for generating positive and negative training examples and extracting relevant features. Explore training the MaxEnt model and decoding sentence examples for relation detection. Build an accurate system for tagging ARG1 in sentences.
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HW7 Extracting Arguments for % Ang Sun asun@cs.nyu.edu March 25, 2012
Outline • File Format • Training • Generating Training Examples • Extracting Features • Training of MaxEnt Models • Decoding • Scoring
File Format • Statistics Canada said service-industry <ARG1> output </ARG1> in August <SUPPORT> rose </SUPPORT> 0.4 <PRED class="PARTITIVE-QUANT"> % </PRED> from July .
Generating Training Examples • Positive Example • Only one positive example for a sentence • The one with the annotation ARG1
Generating Training Examples • Negative Examples • Two methods! • Method 1: consider any token that has one of the following POSs • NN 1150 • NNS 905 • NNP 205 • JJ 25 • PRP 24 • CD 21 • DT 16 • NNPS 13 • VBG 2 • FW 1 • IN 1 • RB 1 • VBZ 1 • WDT 1 • WP 1 Too many negative examples!
Generating Training Examples • Negative Examples • Two methods! • Method 2: only consider head tokens
Extracting Features f: candToken=output
Extracting Features f: tokenBeforeCand=service-industry
Extracting Features f: tokenAfterCand=in
Extracting Features f: tokensBetweenCandPRED=in_August_rose_0.4
Extracting Features f: numberOfTokensBetween=4
Extracting Features f: exisitVerbBetweenCandPred=true
Extracting Features f: exisitSUPPORTBetweenCandPred=true
Extracting Features f: candTokenPOS=NN
Extracting Features f: posBeforeCand=NN
Extracting Features f: posAfterCand=IN
Extracting Features f: possBetweenCandPRED=IN_NNP_VBD_CD
Extracting Features f: BIOChunkChain= I-NP_B-PP_B-NP_B-VP_B-NP_I-NP
Extracting Features f: chunkChain= NP_PP_NP_VP_NP
Extracting Features f: candPredInSameNP=False
Extracting Features f: candPredInSameVP=False
Extracting Features f: candPredInSamePP=False
Extracting Features f: shortestPathBetweenCandPred= NP_NP-SBJ_S_VP_NP-EXT
Training of MaxEnt Model • Each training example is one line • candToken=output . . . . . class=Y • candToken=Canada . . . . . Class=N • Put all examples in one file, the training file • Use the MaxEnt wrapper or the program you wrote in HW5 to train your relation extraction model
Decoding • For each sentence • Generate testing examples as you did for training • One example per feature line (without class=(Y/N)) • Apply your trained model to each of the testing examples • Choose the example with the highest probability returned by your model as the ARG1 • So there should be and must be one ARG1 for each sentence
Scoring • As you are required to tag only one ARG1 for each sentence • Your system will be evaluated based on accuracy • Accuracy = #correct_ARG1s / #sentences