• 호남수학학술지
• /
• 제43권3호
• /
• pp.403-416
• /
• 2021

It is known that the rank 2 stably free syzygy module P⁽²⁾ is not free. This algebraic fact was proved analytically, but this remarkable fact still lacks of a simple algebraic proof. The main purpose of this paper is to give a partially algebraic proof by making use of a theorem whose proof is quite topological, and the further properties of the module will be discussed.

• 대한수학교육학회지:학교수학
• /
• 제4권3호
• /
• pp.347-360
• /
• 2002

This study analyzed the mathematical and didactical contexts of the Euclid's proof about Pythagorean theorem and compared with the teaching methods about Pythagorean theorem in school mathematics. Euclid's proof about Pythagorean theorem which does not use the algebraic methods provide students with the spatial intuition and the geometric thinking in school mathematics. Furthermore, it relates to various mathematical concepts including the cosine rule, the rotation, and the transfor-mation which preserve the area, and so forth. Visual demonstrations can help students analyze and explain mathematical relationship. Compared with Euclid's proof, Algebraic proof about Pythagorean theorem is very simple and it supplies the typical example which can give the relationship between algebraic and geometric representation. However since it does not include various spatial contexts, it forbid many students to understand Pythagorean theorem intuitively. Since both approaches have positive and negative aspects, reciprocal complementary role is required in pedagogical aspects.

• 한국수학교육학회지시리즈A:수학교육
• /
• 제53권1호
• /
• pp.93-110
• /
• 2014

Algebra deals with so general properties about number system that it is called as 'generalized arithmetic'. Observing students' activities in algebra classes, however, we can discover that recognition of the generality in algebraic proofs is not so easy. One of these difficulties seems to be caused by variables which play an important role in algebraic proofs. Many studies show that students have experienced some difficulties in recognizing the meaning and the role of variables in algebraic proofs. For example, the confusion between 2m+2n=2(m+n) and 2n+2n=4n means that students misunderstand independent/dependent variation of variables. This misunderstanding naturally has effects on understanding of the meaning of proofs. Furthermore, students also have a difficulty in making a transition from algebraic proof to numerical cases which have the same structure as the proof. This study investigates whether middle school students can recognize dependent generality and make a transition from proofs to numerical cases. The result shows that the participants of this study have a difficulty in both of them. Based on the result, this study also includes didactical implications for teaching the generality of algebraic proofs.

• 대한수학교육학회지:수학교육학연구
• /
• 제24권3호
• /
• pp.359-374
• /
• 2014

증명 학습과 관련하여 학생들이 경험하는 어려움과 오류는 수학교육계의 난제라 할 만하다. 증명에 대한 형식적 학습이 이루어지는 기하 영역에서뿐만 아니라 대수 증명에 대해서도 문자식의 처리나 일반성의 파악과 관련하여 어려움의 요소는 도처에서 발견된다. 본 연구에서는 두 3의 배수의 합은 3의 배수라는 명제에 대한 문자식을 포함한 증명에서 학생들이 증명의 문맥을 적절하게 이해하는가를 알아보는 데 초점을 둔다. 중학교 3학년 학생 24명을 대상으로 하여 증명 과정에 문자식이 포함되며 결론 부분은 빈 칸으로 생략되어 있는 증명을 제시하고 그 증명이 어떤 명제에 대한 증명인지 알아보도록 한 결과 반 이상의 학생이 문자식 자체에 근거하여 부적절한 응답을 하였다. 나아가 그 중 임의 추출한 세 명을 개별 면담함으로써 사고 특징을 조사하였다. 대수 증명을 식의 성립을 보이는 것으로 간주하는 증명관, 증명 수행과 이해에서의 문자식 해석의 괴리 등을 비롯한 사고 특징을 파악하고 그로부터 교육적 시사점을 도출하였다.

• Journal of applied mathematics & informatics
• /
• 제29권1_2호
• /
• pp.505-510
• /
• 2011

We give a constructive proof that a (partial) evaluation of a multivariate algebraic function with algebraic numbers is again an algebraic function. Especially, we obtain a bound on the degree of an evaluation with the degrees of the original algebraic function and the algebraic numbers evaluated. Furthermore, we show that our bound is sharp with an example.

• 한국수학교육학회지시리즈D:수학교육연구
• /
• 제25권1호
• /
• pp.65-89
• /
• 2022

Despite its recognition in the field of mathematics education and mathematics, students' understanding about proof and performance on proof tasks have been far from promising. Research has documented that teachers tend to accept empirical arguments as proofs. In this study, an online survey was administered to examine how Korean secondary mathematic teachers make judgements on mathematical arguments varied along representations. The results indicate that, when asked to judge how convincing to their students the given arguments would be, the teachers tended to consider how likely students understand the given arguments and this surfaces as a controversial matter with the algebraic argument being both most and least convincing for their students. The teachers' judgements on the algebraic argument were shown to have statistically significant difference with respect to convincingness to them, convincingness to their students, and validity as mathematical proof.

• 한국수학교육학회지시리즈A:수학교육
• /
• 제58권2호
• /
• pp.161-185
• /
• 2019

이 연구에서는 중등 수학 교사와 예비교사들이 추론과 증명을 어떻게 이해하여 구성하는지를 탐색하였다. 연구 참여자들은 대부분 대수적인 증명을 시도하는데 이미 알고 있는 공식이나 식을 적용한 대수적 조작으로 답을 구하는 것에 그치며 주어진 문제에 내재된 수학적 구조를 통해 증명을 구성하지는 못하였다. 또한 참여자의 상당수가 대수적 식을 통한 증명만을 완전한 증명으로 판단하였으며 대부분은 기존에 접하지 못했던 새로운 문제유형에서 추론 및 증명구성을 완성하지 못하는 것으로 나타났다.

• 대한수학회지
• /
• 제44권5호
• /
• pp.1079-1092
• /
• 2007

This paper studies the deformation theory of a holomorphic surjective map from a normal compact complex space X to a compact $K\"{a}hler$ manifold Y. We will show that when the target has non-negative Kodaira dimension, all deformations of surjective holomorphic maps $X{\rightarrow}Y$ come from automorphisms of an unramified covering of Y and the underlying reduced varieties of associated components of Hol(X, Y) are complex tori. Under the additional assumption that Y is projective algebraic, this was proved in [7]. The proof in [7] uses the algebraicity in an essential way and cannot be generalized directly to the $K\"{a}hler$ setting. A new ingredient here is a careful study of the infinitesimal deformation of orbits of an action of a complex torus. This study, combined with the result for the algebraic case, gives the proof for the $K\"{a}hler$ setting.

• 대한수학회지
• /
• 제41권4호
• /
• pp.591-615
• /
• 2004

In this paper, we provide the algebraic foundations to the theory of relative $\ell$$_1$ homology. In particular, we prove that $\ell$$_1$ homology of topological spaces, both for the absolute case and for the relative case, depends only on their fundamental groups. We also provide a .proof of Gromov's Equivalence theorem for $\ell$$_1$ homology, stated by Gromov without proof [4].

• 대한수학회보
• /
• 제46권1호
• /
• pp.67-69
• /
• 2009

Recent work by Gwena and Teixidor i Bigas provides a characteristic-free proof of a part of a previous theorem by one of us, under a stronger numerical assumption. By using an intermediate result from the mentioned manuscript, here we present a simpler, characteristic-free proof of the whole original statement.