... with80.2%F1 for NER and 79.4% Accuracy for NEN.We summarize our contributions as follows.1. We introduce the task of NEN for tweets, and propose jointly conducting NER and NEN for 527tj1···jln, ... knowledge for this task.5.5 DiscussionOne main error source for NER and NEN, whichaccounts for more than half of all the errors, isslang expressions and informal abbreviations. For instance, ... of{fim} and {fijmn}, fim= fim(yi−1m, yim) and fijmn=fijmn(yim, yjn, zijmn); E stands for edges, which de-pends on F , and consists of edges between yi−1m and yim,...