anobiidae's blog

個人的に自然言語処理とかに関して、調べ物したもののメモとかを残す場所。

2012-08-02から1日間の記事一覧

4.1 Upper Bounds for Z(2/2)

H¨older’s inequality describes a class of bounds, for any valid choice of (p, q, r); these values are a design choice of the algorithm. A critical aspect in the choice of bounds is that it must be computationally efficient to maintain. In…

4.1 Upper Bounds for Z(1/2)

FastLDA depends on finding a sequence of improving bounds on the normalization constant, Z1 ≥ Z2 ≥ . . . ≥ ZK = Z. We first define Z in terms of component vectors ~a,~b,~c: FastLDAではZ1 ≥ Z2 ≥ . . . ≥ ZK = Zとなるような正規化定数において…

Fast LDA(3/3)

By organizing the segments in this way, we can obtain a substantial advantage: この方法でsegmentを組織化することで、以下のようなadvantageを得る事が出来る。 we can check each segments in order, knowing only p1 . . . pk and Zk, and if we fin…

Fast LDA(2/3)

Instead of having a single segment for topic k, of length pk/Z = p(zij = k|z¬ij , x, α, β), we instead have several segments skl . . . sk K associated with each topic. pk/Z の長さに基づくtopic kの1つのsegmentの代わりに、我々はそれぞれのt…

Fast LDA(1/3)

大体、CGSのLDAは挙動が解ってきたので、Fast LDAの理解に入る。 http://www.ics.uci.edu/~welling/publications/papers/rtp378-porteous.pdf 4. FAST LDA For most real data sets after several iterations of the Gibbs sampler, the probability mass o…