December 2016
Intermediate to advanced
440 pages
9h 44m
Japanese
Content preview from アルゴリズムクイックリファレンス 第2版
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240
■
7
章
AI
における経路探索
転置表
既に成果のないことが示された計算を繰り返すことを防ぐために、ゲー
ム状態をハッシュしておき、その状態に（開始状態から）到達するのに必
要な経路長を転置表に貯えておくことができる。その状態が後の探索で
現れて、現在の深さが先に見つけられた深さよりも深ければ、探索を停
止する。この方式は、結果的に無駄になってしまう部分木探索を避ける
ことができる。
階層
ゲーム状態が平坦なモデルではなく、階層で表現されるなら、巨大探索
空間をクラスターに再構造化して
A*
探索
を走らせる技法を適用できる。
階層経路探索
A*(HPA*)
は、その一例である（
Botea et al., 2004
）。
メモリ制限
探索空間を計算時間で制限する代わりに、探索中に関係しそうな領域で
の探索に焦点を絞って、他の節点を捨ててしまう「取りこぼしの可能性が
ある」探索方式を選ぶこともできる。単純化メモリ制限
A*
探索
（
SMA*
）
はその一例である（
Russel, 1992
）。
Reinefeld and Marsland
（
1994
）は、興味深い
A*
探索
の各種拡張をまとめてい
る。
AI
システムにおける
A*
探索
の使用については、教科書やさまざまなオンライ
ン情報を参照するとよい（
Barr and Feigenbaum, 1981
）。
7.10
探索木アルゴリズムの比較
幅優先探索
は、多数の手を評価しないといけないが、初期状態から最小手数で解
を見つけることが保証されている。
深さ優先探索
は、常にできる限り前方に進もう
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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.