For example , while it is difficult to induce a grammar with raw text alone , the task is tractable when the syntactic analysis for each sentence is provided as a part of the training data ( Pereira and Schabes 1992 ) .
insideoutside reestimation from partially bracketed corpora
Fernando C N Pereira Yves Schabes
Many learning tasks for natural language processing require supervised training ; that is , the system successfully learns a concept only if it has been given annotated training data . For example , while it is difficult to induce a grammar with raw text alone , the task is tractable when the syntactic analysis for each sentence is provided as a part of the training data ( Pereira and Schabes 1992 ) . Current state-of-the-art statistical parsers ( Collins 1999 ; Charniak 2000 ) are all trained on large annotated corpora such as the Penn Treebank ( Marcus , Santorini , and Marcinkiewicz 1993 ) .
For example , while it is difficult to induce a grammar with raw text alone , the task is tractable when the syntactic analysis for each sentence is provided as a part of the training data ( @@CITATION ) .