5,499 research outputs found
Memory-Efficient Topic Modeling
As one of the simplest probabilistic topic modeling techniques, latent
Dirichlet allocation (LDA) has found many important applications in text
mining, computer vision and computational biology. Recent training algorithms
for LDA can be interpreted within a unified message passing framework. However,
message passing requires storing previous messages with a large amount of
memory space, increasing linearly with the number of documents or the number of
topics. Therefore, the high memory usage is often a major problem for topic
modeling of massive corpora containing a large number of topics. To reduce the
space complexity, we propose a novel algorithm without storing previous
messages for training LDA: tiny belief propagation (TBP). The basic idea of TBP
relates the message passing algorithms with the non-negative matrix
factorization (NMF) algorithms, which absorb the message updating into the
message passing process, and thus avoid storing previous messages. Experimental
results on four large data sets confirm that TBP performs comparably well or
even better than current state-of-the-art training algorithms for LDA but with
a much less memory consumption. TBP can do topic modeling when massive corpora
cannot fit in the computer memory, for example, extracting thematic topics from
7 GB PUBMED corpora on a common desktop computer with 2GB memory.Comment: 20 pages, 7 figure
Perturbative QCD study of decays to a pseudoscalar meson and a tensor meson
We study two-body hadronic decays, with being a light
pseudoscalar (tensor) meson, in the perturbative QCD approach. The CP-averaged
branching ratios and the direct CP asymmetries of the modes are
predicted, where is the difference between the strange numbers of
final and initial states. We also define and calculate experimental observables
for the modes under the mixing, including CP
averaged branching ratios, time-integrated CP asymmetries, and the CP
observables , and . Results are compared to the ones in the literature, and to the ones, which indicate
considerable U-spin symmetry breaking. Our work provides theoretical
predictions for the decays for the first time, some of which will
be potentially measurable at future experiments.Comment: 6 pages, 1 figur
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