Based on this assumption , the problem of identifying mention heads is a sequential phrase identification problem , and we choose to employ the BILOU-representation as it has advantages over traditional BIO-representation , as shown , e.g. in Ratinov and Roth ( 2009 ) .
design challenges and misconceptions in named entity recognition
L Ratinov D Roth
That is , for each mi , j , we have a corresponding head ha , b where i < a < b < j. Moreover , for another head ha ' , b ' , we have the satisfying condition a â b ' > 0 or b â a ' < 0 bha , b , ha ' , b ' . Based on this assumption , the problem of identifying mention heads is a sequential phrase identification problem , and we choose to employ the BILOU-representation as it has advantages over traditional BIO-representation , as shown , e.g. in Ratinov and Roth ( 2009 ) . The BILOUrepresentation suggests learning classifiers that identify the Beginning , Inside and Last tokens of multi-token chunks as well as Unit-length chunks .
Based on this assumption , the problem of identifying mention heads is a sequential phrase identification problem , and we choose to employ the BILOU-representation as it has advantages over traditional BIO-representation , as shown , e.g. in @@CITATION .