April 2020
Intermediate to advanced
344 pages
8h 22m
Japanese
Content preview from Pythonではじめる教師なし学習 ―機械学習の可能性を広げるラベルなしデータの利用
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228
10
章 制限付きボルツマンマシンを用いた推薦システム
図10-2 潜在因子3の行列分解を用いた場合の検証MSEのプロット
MSE
の最小値は
0.765
で、潜在因子が
1
の場合よりも良く、これまでで最良だ。
10.4.3
潜在因子が
5
の場合
潜在因子を
5
にして行列分解モデルを作ってみよう。結果を図 10-3に示す。
図 10-3 潜在因子5の行列分解を用いた場合の検証MSEのプロット
MSE
の最小値は改善していないうえ、
25
エポックあたりから明らかに過剰適合の兆候が見られる。
このあたりで検証誤差が最小となり、その後は増大している。行列分解モデルにこれ以上の容量を与
えてもあまり良いことにはならないだろう。
10.5
RBM
を用いた協調フィルタリング
RBM
に話を戻そう。
RBM
には入力層（もしくは可視層）と隠れ層の
2
層があることを思い出そう。そ
れぞれの層のニューロンは、他の層のニューロンとは接続されるが、同じ層内のニューロンとは接続さ
れない。つまり、層内のニューロン間では通信が行われないということだ。これが
RBM
（制限付きボ
10.5
RBM
を用いた協調フィルタリング
229
ルツマンマシン）の「制限付き」の部分だ。
RBM
のもう
1
つの重要な特徴は、層間の通信が一方向ではなく、双方向に起きることだ。例え
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.