Natural Language Processing · TEE · papers

Q7b · Tagging and two complete parse trees

2023-01-30 · re-exam · recovered AI paper

Previous examination · complete worked answers

Question. Explain POS tagging. Tag and parse (1) John and Mary bought a refrigerator with three doors. (2) It was purchased from a very small store near their house. [10 marks]

Answer

POS tagging assigns grammatical categories in context; constituency parsing groups those words hierarchically. Here with three doors modifies refrigerator; near their house modifies store. These attachments fit the natural reading; the paper gives no fixed CFG.

John/NNP and/CC Mary/NNP bought/VBD a/DT refrigerator/NN with/IN three/CD doors/NNS

SNPNNPJohnCCandNNPMaryVPVBDboughtNPDTaNNrefrigeratorPPINwithNPCDthreeNNSdoors
[S [NP [NNP John] [CC and] [NNP Mary]] [VP [VBD bought] [NP [DT a] [NN refrigerator] [PP [IN with] [NP [CD three] [NNS doors]]]]]]

It/PRP was/VBD purchased/VBN from/IN a/DT very/RB small/JJ store/NN near/IN their/PRP$ house/NN

SNPPRPItVPVBDwasVPVBNpurchasedPPINfromNPDTaADJPRBveryJJsmallNNstorePPINnearNPPRP$theirNNhouse
[S [NP [PRP It]] [VP [VBD was] [VP [VBN purchased] [PP [IN from] [NP [DT a] [ADJP [RB very] [JJ small]] [NN store] [PP [IN near] [NP [PRP$ their] [NN house]]]]]]]]

The first subject is coordinated; bought is past tense. The second VP is passive auxiliary was plus past participle purchased. Very modifies small, and their is a possessive determiner.