In this blog post, we’ll explore the concept of recursion and examine how it’s used in our daily lives through various examples.
Have you heard of Matryoshka dolls? These pot-bellied wooden dolls are one of Russia’s most iconic traditional toys. The feature that most distinguishes them from other dolls is that each one contains a smaller doll that looks just like itself. That smaller doll, in turn, contains yet another smaller doll, and this structure repeats until it reaches the smallest doll. In the field of programming, there is a concept called recursion. Recursion refers to defining an object in a way that references itself. Simply put, it is a structure in which the same structure repeats within itself, much like a matryoshka doll. Programmers use this concept of recursion to design various data structures and define recursive functions.
You’ve probably heard of or seen the concept of a “fractal” at least once. A fractal refers to a recursive geometric structure that exhibits self-similarity. These structures can be found not only in forms artificially generated by programs but also in natural phenomena such as plants, mathematical calculations, and chemical reactions. In complexity science, fractals are used to represent complex chaotic states. Furthermore, fractals are utilized in various artistic fields, such as brand logos and works of art. Currently, if you search for “fractal art” on the internet, you can easily find countless works, and the diverse, colorful shapes are attracting the attention of many people. As such, the concept of recursion has already become familiar to the general public through various media.
One of the most representative structures utilizing recursion is the tree structure. A tree structure refers to a hierarchical arrangement in which, much like a family tree, multiple child nodes are generated from a single root, and each child node in turn has its own child nodes. The folder structure used to store files in an operating system is a prime example. For example, imagine a folder (C:\Program Files) on the local disk (C:) where programs are stored, and within that folder, individual program folders (C:\Program Files\NATEON). Of course, the actual memory structure of a computer is much more complex than this, but users and programmers can easily store, manage, and use the data they need through this tree structure.
Tree structures are actually used to solve a wide variety of problems. One of the most prominent fields is Natural Language Processing (NLP). Languages are broadly categorized into machine language and natural language. Machine language is a language that computers can directly understand and execute; it is generated by translating programming languages and is expressed in binary form. In contrast, natural language refers to languages used by humans, such as Korean, English, and Chinese. Because natural language has highly complex grammatical and semantic structures, it is difficult for computers to understand it as is. Therefore, various processing steps are required to enable computers to understand natural language.
In natural language processing, grammar and context are analyzed to identify dependency relationships between words, and words are linked in a tree structure centered on key meanings. For example, when analyzing a sentence, organizing the relationships between the subject, object, and modifiers hierarchically around the verb clarifies the structure of even long and complex sentences. By representing a sentence as a tree structure in this way, important information can be effectively distinguished from less important information, allowing computers to understand the meaning of the sentence more quickly and accurately.
Natural language processing is currently used in various fields, including machine translation, speech recognition, conversational AI, search engines, document analysis, and automatic summarization. In the past, machine translation and speech recognition were the primary examples, but recently, the scope of application has expanded further due to advancements in generative AI and large-scale language models. Furthermore, in the academic field, it is used for tasks such as document similarity analysis and plagiarism detection. If natural language processing technology continues to advance, intelligent assistant systems capable of naturally understanding human speech and performing various tasks are expected to become even more sophisticated.
While many people may not be familiar with the term “recursion” itself, recursion is already being utilized in many aspects of our daily lives.
Recursive structures help people use systems easily without having to fully understand the complex inner workings of a computer, and they also play a crucial role in structuring complex information so that computers can understand it, much like human language. The greatest advantage of recursion is its ability to organize seemingly complex problems according to specific rules and transform them into simple structures. As technology continues to advance and society becomes increasingly complex, the value and potential applications of recursion will only grow.
