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L02 CFG: Phrase struc trees to meaning PHRASE STRUCTURE TREE to MEANING o Relating a phrase structure tree to a modifier-modified tree o Example sentence 1: 'arrow of son of Dasarath' * Phrase structure tree 1: NP_1 | .--------------. | | | n of NP_2 | | | .----------. arrow | | | n of NP_3 | | son n-proper | Dasarath o Notion of the head of a phrase - What is the head of NP_1 ? + Consider Ex. The arrow of son of Dasarath is sharp - Who/what is sharp: arrow, son, Dasarath? . Ans: Arrow. Therefore, 'arrow' is the head of NP_1 + Consider Ex. The son of Dasarath is sincere. - Who is sincere: Son, Dasarath? . Ans: Son. Therefore, 'son' is the head of NP_2 * Head of a phrase is determined by rules of the language: - In case of NPs with 'of' in English, the noun on the left is the head. o Modifier-modified tree 1 (for the example on the top): arrow | |of | son | |of | Dasarath o Example sentence 2: 'Ram saw Mohan' * Phrase structure tree: S | .----------. | | NP VP | | | .------. n-proper | | | v NP Ram | | saw n-proper | Ram * Modifier-modified tree: saw | .-----. |k1 |k2 | | Ram Mohan o Rules can be prepared for converting from ps-tree to mm-tree (later)..........................................NEXT PREVIOUS INDEX