• Journal for History of Mathematics
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• v.29 no.3
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• pp.147-155
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• 2016

Ancient books from East Asia, especially, Korea, China and Japan, are all written in Chinese. Ancient mathematical books like 九章算術(Gujang Sansul in Korean sound, Jiuzhang Suanshu in Chinese) is not exceptional and also was written in Chinese. The book 九章算術音義(Gujang Sansul Eumeui in Korean, Jiuzhang Suanshu Yinyi in Chinese), a dictionary-like book on 九章算術was published by official 李籍(Lǐ Jí) of 唐(Tang) dynasty (AD 618-907). We discuss how to pronounce Chinese characters based on 九章算術音義. To do so, we compare the pronunciation of the characters used in the words which are explained in 九章算術音義, to those of the current Korean and Chinese. Surprisingly, the pronunciations of the Chinese characters are almost all accordant with those of both Korean and Chinese.

• Journal for History of Mathematics
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• v.28 no.5
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• pp.207-231
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• 2015

We discuss several issues relating to the meaning of the terms and phrases in the first half of Chapter One fang tian 方田章 of ${\ll}$Jiuzhang suanshu九章算術${\gg}$. I understood those issues more clearly in the course of the translation of ${\ll}$Kujang sulhae 九章術解${\gg}$. Those are '今有' in the beginning of each problem, '積' and '冪' in the method of square field 方田術, '齊' in the method of reduction to a common denominator 齊同術, '經' and '有分者通之重有分者同而通之' in the method of dividing fraction 經分術, '實如法而一' in the calculation using the rods, '兩邪' in the method of trapezium field with a perpendicular side 邪田術. We may find out the value of ${\ll}$Kujang sulhae 九章術解${\gg}$ through our discussion.

• Journal for History of Mathematics
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• v.29 no.6
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• pp.317-324
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• 2016

Since Jiuzhang Suanshu, mathematical structures in the traditional East Asian mathematics have been revealed by practical problems. Since then, polynomial equations are mostly the type of $p(x)=a_0$ where p(x) has no constant term and $a_0$ is a positive number. This restriction for the polynomial equations hinders the systematic development of theory of equations. Since tianyuanshu (天元術) was introduced in the 11th century, the polynomial equations took the form of p(x) = 0, but it was not universally adopted. In the mean time, East Asian mathematicians were occupied by kaifangfa so that the concept of zeros of polynomials was not materialized. We also show that Suanxue Qimeng inflicted distinct developments of the theory of equations in three countries of East Asia.

• Journal for History of Mathematics
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• v.18 no.3
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• pp.25-38
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• 2005

We briefly survey the history of Chinese mathematics which concerns the resolution of right triangles. And we analyse the problems Yucigugosulyodohae(劉氏勾股述要圖解) which is the mathematical book of Chosun Dynasty and contains the 224 problems about right triangles only. Among them, 210 problems are for resolution of right triangles. We also present the methods for generating the Pythagorean triples and constructing polynomial equations in Yucigugosulyodohae which are needed for resolving right triangles.

• Journal for History of Mathematics
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• v.27 no.2
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• pp.101-110
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• 2014

Joseon is mainly an agricultural country and its main source of national revenue is the farmland tax. Since the beginning of the Joseon dynasty, the assessment and taxation of agricultural land became one of the most important subjects in the national administration. Consequently, the measurement of fields, or the area of various plane figures and curved surfaces is a very much important topic for mathematical officials. Consequently Joseon mathematicians were concerned about the volumes of solids more for those of granaries than those of earthworks. The area and volume together with surveying have been main geometrical subjects in Joseon mathematics as well. In this paper we discuss the history of volumes of solids in Joseon mathematics and the influences of Chinese mathematics on the subject.

• Journal for History of Mathematics
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• v.27 no.6
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• pp.387-394
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• 2014

Since ancient civilization, solving equations has become one of the most important subjects in mathematics and mathematics education. The extractions of square roots and cube roots were first dealt in Jiuzhang Suanshu in the setting of subdivisions. Extending these, Shisuo Kaifangfa and Zengcheng Kaifangfa were introduced in the 11th century and the subsequent development became one of the most important contributions to mathematics in the East Asian mathematics. The translation of coordinate axes plays an important role in school mathematics. Connecting the translation and Kaifangfa, we find strong didactical implications for improving students' understanding the history of Kaifangfa together with the translation itself although the latter is irrelevant to the former's historical development.

• Journal for History of Mathematics
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• v.28 no.6
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• pp.301-310
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• 2015

Since Jiuzhang Suanshu, the main tools in the theory of right triangles, known as Gougushu in East Asia were algebraic identities about three sides of a right triangle derived from the Pythagorean theorem. Using tianyuanshu up to siyuanshu, Song-Yuan mathematicians could skip over those identities in the theory. Chinese Mathematics in the 17-18th centuries were mainly concerned with the identities along with the western geometrical proofs. Jeong Yag-yong (1762-1836), a well known Joseon scholar and writer of the school of Silhak, noticed that those identities can be derived through algebra and then wrote Gugo Wonlyu (勾股源流) in the early 19th century. We show that Jeong reveals the algebraic structure of polynomials with the three indeterminates in the book along with their order structure. Although the title refers to right triangles, it is the first pure algebra book in Joseon mathematics, if not in East Asia.

• Journal for History of Mathematics
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• v.33 no.6
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• pp.303-314
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• 2020

Extending the method of extractions of square and cube roots in Jiuzhang Suanshu, Jia Xian introduced zengcheng kaifangfa in the 11th century. The process of zengcheng kaifangfa is exactly the same with that in Ruffini-Horner method introduced in the 19th century. The latter is based on the synthetic divisions, but zengcheng kaifangfa uses the binomial expansions. Since zengcheng kaifangfa is based on binomial expansions, traditional mathematicians in East Asia could not relate the fact that solutions of polynomial equation p(x) = 0 are determined by the linear factorization of p(x). The purpose of this paper is to reveal the difference between the mathematical structures of zengcheng kaifangfa and Ruffini-Honer method. For this object, we first discuss the reasons for zengcheng kaifangfa having difficulties to connect solutions with linear factors. Furthermore, investigating multiple solutions of equations constructed by tianyuanshu, we show differences between two methods and the structure of word problems in the East Asian mathematics.