September 2014
Intermediate to advanced
336 pages
7h 53m
Japanese
Content preview from アンダースタンディング コンピュテーション ―単純な機械から不可能なプログラムまで
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136
5
章 究極の機械
がありました。スタックをもっと柔軟なストレージに置き換えることによって、そうした制限を取り除
き、機械の能力を高めることができます。
5.1.1
ストレージ
計算は通常、紙の上に特定のシンボルを書くことで実行されます。この紙は子供が使う算数ノートの
ように、マス目で区切られているものとします。算数では紙の
2
次元特性を利用することがあります
が、それは常に回避可能であり、紙の
2
次元特性は計算にとって不可欠なものではないことに同意で
きるでしょう。計算は
1
次元の紙、すなわちマス目で区切られたテープ上で実行されるものとします。
―
アラン・チューリング「
On Computable Numbers, with an Application to the
Entscheidungsproblem
」（
http://dx.doi.org/10.1112/plms/s2-42.1.230
）
チューリングのとった解決策は、機械に無限の長さの空白のテープ（事実上、必要に応じて両端を伸
ばせる1次元配列）を持たせて、テープの任意の場所に文字を読み書きできるようにすることでした。
この1 本のテープがストレージと入力の両方の役割を果たします。事前に、そのテープを入力として扱
う文字列で埋めておきます。機械は計算を実行しながら、そのテープにある文字を読み、必要に応じ
て上書きすることができます。
この無限の長さのテープにアクセスする有限状態機械のことを、チューリングマシン（TM：Turing
Machi
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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.