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The left corner of a production rule in a context-free grammar is the left-most symbol on the right side of the rule.〔(9.3 Using Left-corner Tables ), Patrick Blackburn and Kristina Striegnitz, Natural Language Processing Techniques in Prolog〕 For example, in the rule ''A→Xα'', ''X'' is the left corner. The left corner table associates a symbol with all possible left corners for that symbol, and the left corners of those symbols, etc. Given the grammar :S→VP :S→NP VP :VP→V NP :NP→DET N Left corners are used to add bottom-up filtering of a top-down parser. You can use the left corners to do top-down filtering of a bottom-up parser. ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Left corner」の詳細全文を読む スポンサード リンク
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