Zeros of Polynomials in East Asian Mathematics

홍성사,홍영희,김창일,Hong, Sung Sa,Hong, Young Hee,Kim, Chang Il The Korean Society for History of Mathematics 2016 Journal for history of mathematics Vol.29 No.6

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.

Hong JeongHa's Tianyuanshu and Zhengcheng Kaifangfa

홍성사,홍영희,김영욱,Hong, Sung Sa,Hong, Young Hee,Kim, Young Wook The Korean Society for History of Mathematics 2014 Journal for history of mathematics Vol.27 No.3

Tianyuanshu and Zengcheng Kaifangfa introduced in the Song-Yuan dynasties and their contribution to the theory of equations are one of the most important achievements in the history of Chinese mathematics. Furthermore, they became the most fundamental subject in the history of East Asian mathematics as well. The operations, or the mathematical structure of polynomials have been overlooked by traditional mathematics books. Investigation of GuIlJib (九一集) of Joseon mathematician Hong JeongHa reveals that Hong's approach to polynomials is highly structural. For the expansion of $\prod_{k=11}^{n}(x+a_k)$, Hong invented a new method which we name Hong JeongHa's synthetic expansion. Using this, he reveals that the processes in Zhengcheng Kaifangfa is not synthetic division but synthetic expansion.

이상혁(李尙爀)의 차근방몽구(借根方蒙求)와 수리정온(數理精蘊)

홍성사,홍영희,Hong, Sung-Sa,Hong, Young-Hee 한국수학사학회 2008 Journal for history of mathematics Vol.21 No.4

이 논문은 이상혁(李尙爀)$(1810{\sim}?)$의 차근방몽구(借根方蒙求)와 수리정온(數理精蘊), 매구성(梅구成) 적수유진(赤水遺珍)과의 관계를 조사하여 이상혁(李尙爀) 서양 수학을 받아들이는 과정과 이를 확장하여 그의 대수학의 기초를 이루는 과정을 연구한다. In this paper, we investigate Lee Sang Hyuk (李尙爀, $1810{\sim}?$)'s first mathematical work ChaGeunBangMongGu(借根方蒙求, 1854) and its relation with Shu li jing yun and Chi shui yi zhen. We then study an influence of western mathematics for establishing his study on algebra.

조선(朝鮮) 산학(算學)의 퇴타술

홍성사,Hong Sung-Sa 한국수학사학회 2006 Journal for history of mathematics Vol.19 No.2

조선 산학의 퇴타술의 역사를 연구한다. 이상혁(李尙爀)$(1810\sim?)$의 익산(翼算)(1868)이 출판되기 전의 역사와 익산(翼算)의 결과로 나누어 연구한다. 경선징(慶善徵)$(1616\sim?)$의 묵사집산법(默思集算法)부터 남병길(南秉吉)$(1820\sim1869)$의 산학정의(算學正義)(1867)까지의 산서를 통하여 익산(翼算) 이전의 퇴타술은 큰 발전을 이루지 못한 것을 조사한다. 이상혁(李尙爀)은 조선(朝鮮) 산학(算學)에서 가장 독창적인 방법을 써서 새로운 결과를 얻어낸다. 그는 퇴타술을 구조적으로 해결하고, 또 새로운 문제인 절적(截積)과 이를 위한 분적법(分積法)을 도입하여 이의 구조도 완전히 밝혀내었다. We study the theory of finite series in Chosun Dynasty Mathematics. We divide it into two parts by the publication of Lee Sang Hyuk(李尙爀, 1810-?)'s Ik San(翼算, 1868) and then investigate their history. The first part is examined by Gyung Sun Jing(慶善徵, 1616-?)'s Muk Sa Jib San Bub(默思集算法), Choi Suk Jung(崔錫鼎)'s Gu Su Ryak(九數略), Hong Jung Ha(洪正夏)'s Gu Il Jib(九一集), Cho Tae Gu(趙泰耉)'s Ju Su Gwan Gyun(籌書管見), Hwang Yun Suk(黃胤錫)'s San Hak Ib Mun(算學入門), Bae Sang Sul(裵相設)'s Su Gye Soe Rok and Nam Byung Gil(南秉吉), 1820-1869)'s San Hak Jung Ei(算學正義, 1867), and then conclude that the theory of finite series in the period is rather stable. Lee Sang Hyuk obtained the most creative results on the theory in his Ik San if not in whole mathematics in Chosun Dynasty. He introduced a new problem of truncated series(截積). By a new method, called the partition method(分積法), he completely solved the problem and further obtained the complete structure of finite series.

Jo Tae-gu's Juseo Gwan-gyeon and Jihe Yuanben

홍성사,홍영희,김창일,Hong, Sung Sa,Hong, Young Hee,Kim, Chang Il The Korean Society for History of Mathematics 2018 Journal for history of mathematics Vol.31 No.2

Matteo Ricci and Xu Gwangqi translated the first six Books of Euclid's Elements and published it with the title Jihe Yuanben, or Giha Wonbon in Korean in 1607. It was brought into Joseon as a part of Tianxue Chuhan in the late 17th century. Recognizing that Jihe Yuanben deals with universal statements under deductive reasoning, Jo Tae-gu completed his Juseo Gwan-gyeon to associate the traditional mathematics and the deductive inferences in Jihe Yuanben. Since Jo served as a minister of Hojo and head of Gwansang-gam, Jo had a comprehensive understanding of Song-Yuan mathematics, and hence he could successfully achieve his objective, although it is the first treatise of Jihe Yuanben in Joseon. We also show that he extended the results of Jihe Yuanben with his algebraic and geometric reasoning.

Chosun Mathematics in the early 18th century

홍성사,홍영희,Hong, Sung-Sa,Hong, Young-Hee The Korean Society for History of Mathematics 2012 Journal for history of mathematics Vol.25 No.2

1592년과 1636년 양대 전란으로 전통적인 조선 산학의 결과는 거의 소멸되어, 17세기 중엽 조선 산학은 새로 시작할 수밖에 없었다. 조선은 같은 시기에 청으로 부터 도입된 시헌력(時憲曆, 1645)을 이해하기 위하여 서양수학에 관련된 자료를 수입하기 시작하였다. 한편 전통 산학을 위하여 김시진(金始振, 1618-1667)은 산학계몽(算學啓蒙, 1299)을 중간(重刊)하였다. 이들의 영향으로 이루어진 조태구(趙泰耉, 1660-1723)의 주서관견(籌書管見)과 홍정하(洪正夏, 1684-?)의 구일집(九一集)을 함께 조사하여 이들이 조선 산학의 발전에 새로운 전기를 마련한 것을 보인다. After disastrous foreign invasions in 1592 and 1636, Chosun lost most of the traditional mathematical works and needed to revive its mathematics. The new calendar system, ShiXianLi(時憲曆, 1645), was brought into Chosun in the same year. In order to understand the system, Chosun imported books related to western mathematics. For the traditional mathematics, Kim Si Jin(金始振, 1618-1667) republished SuanXue QiMeng(算學啓蒙, 1299) in 1660. We discuss the works by two great mathematicians of early 18th century, Cho Tae Gu(趙泰耉, 1660-1723) and Hong Jung Ha(洪正夏, 1684-?) and then conclude that Cho's JuSeoGwanGyun(籌 書管見) and Hong's GuIlJib(九一集) became a real breakthrough for the second half of the history of Chosun mathematics.

Mathematics in the Joseon farmland tax systems

홍성사,홍영희,김창일,Hong, Sung Sa,Hong, Young Hee,Kim, Chang Il The Korean Society for History of Mathematics 2015 Journal for history of mathematics Vol.28 No.2

The Joseon dynasty (1392-1910) is basically an agricultural country and therefore, the main source of her national revenue is the farmland tax. Thus the farmland tax system becomes the most important state affair. The 4th king Sejong establishes an office for a new law of the tax in 1443 and adopts the farmland tax system in 1444 which is legalized in Gyeongguk Daejeon (1469), the complete code of law of the dynasty. The law was amended in the 19th king Sukjong era. Jo Tae-gu mentioned the new system in his book Juseo Gwan-gyeon (1718) which is also included in Sok Daejeon (1744). Investigating the mathematical structures of the two systems, we show that the systems involve various aspects of mathematics and that the systems are the most precise applications of mathematics in the Joseon dynasty.

Haidao Suanjing in Joseon Mathematics

홍성사,홍영희,김창일 한국수학사학회 2019 Journal for history of mathematics Vol.32 No.6

Haidao Suanjing was introduced into Joseon by discussion in Yang Hui Suanfa (楊輝算法) which was brought into Joseon in the 15th century. As is well known, the basic mathematical structure of Haidao Suanjing is perfectly illustrated in Yang Hui Suanfa. Since the 17th century, Chinese mathematicians understood the haidao problem by the Western mathematics, namely an application of similar triangles. The purpose of our paper is to investigate the history of the haidao problem in the Joseon Dynasty. The Joseon mathematicians mainly conformed to Yang Hui's verifications. As a result of the influx of the Western mathematics of the Qing dynasty for the study of astronomy in the 18th century Joseon, Joseon mathematicians also accepted the Western approach to the problem along with Yang Hui Suanfa.

조선 산학자 이상혁의 방정식론

홍성사,홍영희 한국수학사학회 2004 Journal for history of mathematics Vol.17 No.1

Iksan(翼算) written by Lee Sang Hyuk(李相赫, 1810∼\ulcorner) is unique among mathematical books published in Chosun Dynasty since it is the only book which accomplishes the conceptualization of theory of equations if not that of mathematics itself. We investigate its process by his other publications and mathematical interaction with Nam Byung Gil(南秉吉, 1820∼1869).

Zengcheng Kaifangfa and Zeros of Polynomials

홍성사,홍영희,김창일 한국수학사학회 2020 Journal for history of mathematics Vol.33 No.6

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 expansions of 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.