Once Upon an Algorithm: How Stories Explain Computing

How Hansel and Gretel, Sherlock Holmes, the movie Groundhog Day, Harry Potter, and other familiar stories illustrate the concepts of computing.

Picture a computer scientist, staring at a screen and clicking away frantically on a keyboard, hacking into a system, or perhaps developing an app. Now delete that picture. In Once Upon an Algorithm, Martin Erwig explains computation as something that takes place beyond electronic computers, and computer science as the study of systematic problem solving. Erwig points out that many daily activities involve problem solving. Getting up in the morning, for example: You get up, take a shower, get dressed, eat breakfast. This simple daily routine solves a recurring problem through a series of well-defined steps. In computer science, such a routine is called an algorithm.

Erwig illustrates a series of concepts in computing with examples from daily life and familiar stories. Hansel and Gretel, for example, execute an algorithm to get home from the forest. The movie Groundhog Day illustrates the problem of unsolvability; Sherlock Holmes manipulates data structures when solving a crime; the magic in Harry Potter's world is understood through types and abstraction; and Indiana Jones demonstrates the complexity of searching. Along the way, Erwig also discusses representations and different ways to organize data; "intractable" problems; language, syntax, and ambiguity; control structures, loops, and the halting problem; different forms of recursion; and rules for finding errors in algorithms.

This engaging book explains computation accessibly and shows its relevance to daily life. Something to think about next time we execute the algorithm of getting up in the morning.

《一個演算法的童話》這本書講述了演算法的概念，並以《韓塞爾與葛雷特》、《福爾摩斯探案集》、電影《重返初戀日》、《哈利波特》等熟悉的故事來說明計算的概念。這本書解釋了計算不僅僅發生在電子計算機中，而且計算科學是研究系統性問題解決的學科。作者馬丁·厄維格指出，許多日常活動都涉及問題解決，例如早上起床：起床、洗澡、穿衣服、吃早餐。這個簡單的日常例行程序通過一系列明確的步驟解決了一個重複出現的問題，而在計算科學中，這樣的例行程序被稱為演算法。厄維格通過日常生活和熟悉的故事舉例說明了計算的一系列概念。例如，《韓塞爾與葛雷特》通過執行一個演算法來從森林回家，《重返初戀日》展示了無法解決的問題，《福爾摩斯探案集》中的福爾摩斯在解決犯罪時操作數據結構，《哈利波特》的魔法通過類型和抽象來理解，而印第安納·瓊斯則展示了搜索的複雜性。在這過程中，厄維格還討論了數據的表示和不同的組織方式；“棘手”的問題；語言、語法和歧義；控制結構、循環和停機問題；不同形式的遞歸；以及查找演算法中錯誤的規則。這本引人入勝的書以易懂的方式解釋了計算並展示了它對日常生活的重要性。下次早上起床時，可以思考一下執行演算法的過程。

Martin Erwig is Professor of Computer Science in the School of Electrical Engineering and Computer Science at Oregon State University.

Martin Erwig 是俄勒岡州立大學電機工程與電腦科學學院的計算機科學教授。