• Bulletin of the Korean Mathematical Society
• /
• v.36 no.3
• /
• pp.503-512
• /
• 1999

Over a field k, every schur k-algebra is a cyclotomic algebra due to Brauer-Witt theorem. Similarly every projective Schur k-division algebra is itself a radical algebra by Aljadeff-Sonn theorem. We study the two theorems over a certain commutative ring, and prove similar results over regular domain containing a field.

• Journal of the Korean Mathematical Society
• /
• v.43 no.6
• /
• pp.1301-1324
• /
• 2006

The affine homogeneous hypersurface in ${\mathbb{R}}^{n+1}$, which is a graph of a function $F:{\mathbb{R}}^n{\rightarrow}{\mathbb{R}}$ with |det DdF|=1, corresponds to a complete unimodular left symmetric algebra with a nondegenerate Hessian type inner product. We will investigate the condition for the domain over the homogeneous hypersurface to be homogeneous through an extension of the complete unimodular left symmetric algebra, which is called the graph extension.

• Communications of the Korean Mathematical Society
• /
• v.22 no.3
• /
• pp.419-428
• /
• 2007

In this paper, we will investigate the Hessian geometry of the homogeneous domain over the hypersurface given by a function F : $\mathbb{R}^n{\rightarrow}\mathbb{R}$ with ${\mid}{\det}\;DdF\mid=1$.

• The Mathematical Education
• /
• v.41 no.3
• /
• pp.233-256
• /
• 2002

This study investigated school mathematics curriculum of England, newly revised in 1998, focused on the 'number and algebra' domain among three major domains of the English curriculum. On the basis of its understanding, this domain was compared and analyzed with school mathematics curriculum of Korea. In doing so, this study explored its plans and procedures and established a frame of comparison for the curriculums between the two countries. The structure of the National Curriculum in England is composed of programmes of study and attainment targets. The former sets out what should be taught in mathematics at key stages 1, 2, 3, and 4 and provides the basis for planning schemes of work, and the latter sets out the knowledge, skills, and understanding that pupils of different abilities and matures are expected to have by the end of each key stage. Attainment targets are composed of eight levels and an additional level of increasing difficulty. According to the results of the present study, Korea focuses on the formal and systematic mathematical knowledge on the basis of sound understanding of certain mathematical terms or concepts. On the other hand, England tends to deal with numbers more flexibly and naturally through the aquisition of mental methods, calculator use methods, etc, and emphasizes that mathematics be realistic and useful in solving a diverse number of problems confronted in everyday life.

• Journal of Educational Research in Mathematics
• /
• v.17 no.3
• /
• pp.253-270
• /
• 2007

by A.C. Clairaut was written based on the historico-genetic principle such as his . In this paper, by analyzing his we can induce six principles that Clairaut adopted to teach algebra: necessity and curiosity as a motive of studying algebra, harmony of discovery and proof, complementarity of generalization and specialization, connection of knowledge to be learned with already known facts, semantic approaches to procedural knowledge of mathematics, reversible approach. These can be considered as strategies for teaching algebra accorded with beginner's mind. Some of them correspond with characteristics of , but the others are unique in the domain of algebra. And by comparing Clairaut's approaches with school algebra, we discuss about some mathematical subjects: setting equations in relation to problem situations, operations and signs of letters, rule of signs in multiplication, solving quadratic equations, and general relationship between roots and coefficients of equations.

• Journal of the Korean Mathematical Society
• /
• v.34 no.3
• /
• pp.633-651
• /
• 1997

For a non-degenerate symmetric bilinear form $\sigma$ on a finite dimensional vector space E, the Jordan algebra of $\sigma$-symmetric operators has a symmetric cone $\Omega_\sigma$ of positive definite operators with respect to $\sigma$. The cone $C_\sigma$ of elements (x,y) \in E \times E with \sigma(x,y) \geq 0$ gives the compression semigroup. In this work, we show that in the sutomorphism group of the tube domain over $\Omega_\sigma$, this semigroup has a UDL and Ol'shanskii decompositions and is exactly the compression semigroup of $\Omega_sigma$.

• Bulletin of the Korean Mathematical Society
• /
• v.26 no.2
• /
• pp.135-137
• /
• 1989

Let R be a Krull domain with field of fractions K. By Br(R) we denote the Brauer group of R. Studying the Kernel of the homomorphism Br(R).rarw.Br(K), Orzech defined Brauer groups Br(M) for different categories M of R-modules [4]. In this paper we show that an algebra A in Br(D) is a maximal order in A K and that the map Br(D).rarw. Br(K) is one to one. We note here few conventions. All rings are Krull domains and all modules will be unitary. By Z we donote the set of height one prime ideals of a Krull domain.

• Bulletin of the Korean Mathematical Society
• /
• v.61 no.3
• /
• pp.735-744
• /
• 2024

In this note, we shed new light on Krull domains from the point view of Gorenstein homological algebra. By using the so-called w-operation, we show that an integral domain R is Krull if and only if for any nonzero proper w-ideal I, the Gorenstein global dimension of the w-factor ring (R/I)_w is zero. Further, we obtain that an integral domain R is Dedekind if and only if for any nonzero proper ideal I, the Gorenstein global dimension of the factor ring R/I is zero.

• Journal of the Korean Mathematical Society
• /
• v.58 no.6
• /
• pp.1311-1325
• /
• 2021

One says that a ring homomorphism R → S is Ohm-Rush if extension commutes with arbitrary intersection of ideals, or equivalently if for any element f ∈ S, there is a unique smallest ideal of R whose extension to S contains f, called the content of f. For Noetherian local rings, we analyze whether the completion map is Ohm-Rush. We show that the answer is typically 'yes' in dimension one, but 'no' in higher dimension, and in any case it coincides with the content map having good algebraic properties. We then analyze the question of when the Ohm-Rush property globalizes in faithfully flat modules and algebras over a 1-dimensional Noetherian domain, culminating both in a positive result and a counterexample. Finally, we introduce a notion that we show is strictly between the Ohm-Rush property and the weak content algebra property.

• Journal of the Korean School Mathematics Society
• /
• v.13 no.2
• /
• pp.243-262
• /
• 2010

CRESST(the National Center for Research on Evaluation, Standards, and Student Testing at UCLA) is now carrying out the research, which was scheduled for a five year period from 2007 to 2011. This research aimed at testing the effectiveness of the formative assessment program by continuously conducting the program on the target group and steadily applying the recurring feedback, in order to reform the teachers' teaching and to facilitate students' learning. To do this, CRESST has set out to develop the material for 7th graders since January 2007, and KICE(Korea Institute of Curriculum and Evaluation) have been running a collaborated research since July 2007, while sharing the instructional materials developed by CRESST. In 2008, the pre-test was conducted prior to this study in 2009. Especially, this paper deals with the Korean 7th graders' scholastic achievements in algebra domain measured by PowerSource(c). In addition, this study would examine the responses of teachers and students on its application.