Báo cáo khoa học: "Viterbi Training for PCFGs: Hardness Results and Competitiveness of Uniform Initialization" doc

... solving and even ap- proximating Viterbi training for PCFGs is NP-hard. We motivate the use of uniform- at-random initialization for Viterbi EM as an optimal initializer in absence of further information ... hardness result for Viterbi training. §5 extends this result to a hardness result of approximation and §6 further extends these results for other cases. §7 de...

Ngày tải lên: 17/03/2014, 00:20

... between the chelatase and methyltrans- ferase has important implications for regulation of chlorophyll biosynthesis and for the availability of magnesium protoporphyrin for plastid-to-nucleus signalling. Abbreviations Mg ... another layer of complexity to both the regulation of chlorophyll biosynthesis, and the availability of MgP for signalling to the nucleus. We sugg...

Ngày tải lên: 20/02/2014, 02:21

... In In The Proceedings of Eu- ropean Languages and the Implementation of Com- munication and Information Technologies (Elicit). M. Bradley and P. Lang. 1999. Affective forms for english words (anew): ... 1,163 Table 8: An overlap of concepts by part -of- speech tag between CLEX and existing lexicons. CLEX∩GI stands for the intersection of sets, CLEX\GI denotes the differen...

Ngày tải lên: 22/02/2014, 02:20

... Medline abstracts used for self -training were chosen ran- domly and thus span a large number of biomed- ical sub-domains. The results, the central results of this paper, are shown in Figure 1. Clegg and Shepherd (2005) ... McClosky et al., 2006b). One possible use for this technique is for parser adaptation — initially training the parser on one type of data for which...

Ngày tải lên: 20/02/2014, 09:20

... each iteration of the algorithm: One for training and the other for development (65% and 35% respectively). We train the learners with the training set and we evaluate the performance to pick ... subset of features. We have used 175 examples for the training set (used to select the best features) and 140 for the test set (used to measure the performance). The...

Ngày tải lên: 20/02/2014, 16:20

... [2]. An unintended side effect of modern technological advances has been the plausibility of maintaining moribund patients in a state of suspended animation for prolonged and sometimes indefinite periods ... treatment for the terminally ill: the ‘risk of unacceptable badness’ David Crippen Associate Professor, Director, Neurovascular ICU, Department of Critical Care Medicine,...

Ngày tải lên: 25/10/2012, 10:45

... backoff methods, all in- stances of α = 1 and all instances of β = 0. The pure backoff methods we consider are Katz back- off and backoff absolute discounting, due to Ney et al. 2 In Katz backoff, ... probability of a word w n , given the preceding context w 1 . w n−1 , to be the ratio of the num- ber of occurrences in a training corpus of the N- gram w 1 . w n to the total...

Ngày tải lên: 20/02/2014, 09:20

... helices A V and B V at the surface of domain V. Gly621 and Gly617 are in the area of contact with the 1095 and 2473 regions of 23S RNA. The two helices are facing the ribosome, and the four-stranded ... Pro404 and Pro406 are critical for this conformation. His438, within hydrogen-bonding dis- tance of Glu405 and the carbonyl group of Pro404, also contributes to this pa...

Ngày tải lên: 06/03/2014, 22:21

... the instances of C1 and the instances of C2 do not share a value. • Two classes C1 and C2 are contrasted by a nu- meric feature if the ranges of the instances of C1 and of C2 do not overlap. ... nature of the discrimination subtask, isolated this part of the program, which was later extended with the mechanisms for derived features and partial con- trasts. Som...

Ngày tải lên: 08/03/2014, 06:20

... processing and statistical sentiment modeling informed by, and contributing to, an understanding of the cultural and political practices at work through the use of Twitter. 3 The System For accuracy ... delivering results instantly and continuously. It offers the public, the media, politicians and scholars a new and timely perspective on the dynamics of the elect...

Ngày tải lên: 16/03/2014, 20:20