• East Asian mathematical journal
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• v.24 no.1
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• pp.11-20
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• 2008

We survey recent results and some conjectures in analytical fixed point theory. We list the known fixed point theorems for Kakutani maps, Fan-Browder maps, locally selectionable maps, approximable maps, admissible maps, and the better admissible class $\cal{B}$ of maps. We also give 16 conjectures related to that theory.

• Journal of the Korean Operations Research and Management Science Society
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• v.36 no.3
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• pp.27-43
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• 2011

This paper investigates properties of the newsvendor problem under a schedule involving progressive multiple discounts compared with the standard newsvendor problem under a no-discounts schedule. Unlike most conventional approaches using the criticial fractile to analyze the retailer and/or supplier behavior(s) in the newsvendor problem, our approach uses riskless profit. From the properties revealed through a series of computational experiments, two conjectures regarding the relationship between the expected profits of both newsvendor problems as a generalization over Khouja's argument (1995) are raised. Those conjectures encourage newsvendors who may face budget or warehouse capacity restriction to use the extended model under a multiple-discounts schedule rather than the standard model with no-discounts schedule because they apply for every order quantity as well as the optimal order quantity. In addition to the conjectures, some insightful results are found to justify the implementation of a multiple-discounts schedule from the computational experiments and a new interpretation for implementation of a multiple-discounts schedule that has not been addressed in Khouja is provided.

• Honam Mathematical Journal
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• v.30 no.1
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• pp.47-51
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• 2008

By finding two characters of subgroups of the Heisenberg group $H_{27}$ whose induced characters are same, we prove that the Birch and Swinnerton-Dyer conjectures for two elliptic curves corresponding to the characters are equivalent.

• Bulletin of the Korean Mathematical Society
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• v.56 no.2
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• pp.501-504
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• 2019

In this note, we prove that Gluck's conjecture, Isaacs-Navarro-Wolf Conjecture and Taketa's inequality are true for solvable groups whose character graphs having diameter 3.

• Journal of the Korean Mathematical Society
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• v.51 no.5
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• pp.987-1028
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• 2014

In a recent systematic study, C. Sandon and F. Zanello offered 30 conjectured identities for partitions. As a consequence of their study of partition identities arising from Ramanujan's formulas for multipliers in the theory of modular equations, the present authors in an earlier paper proved three of these conjectures. In this paper, we provide proofs for the remaining 27 conjectures of Sandon and Zanello. Most of our proofs depend upon known modular equations and formulas of Ramanujan for theta functions, while for the remainder of our proofs it was necessary to derive new modular equations and to employ the process of duplication to extend Ramanujan's catalogue of theta function formulas.

• School Mathematics
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• v.7 no.4
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• pp.319-336
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• 2005

This study is to find the properties of Diffy activity and to investigate the problems and conjectures which could be posed in the Diffy activity. The Diffy is a simple subtracting activity. But, 1 think it is a field where the mathematical thinking can take place. I proposed some problems and conjectures which can be posed. I solved the problems using excel and the software I developed and proposed the related data. I think such problems and the data will be the good materials for elementary students and gifted to think mathematically with.

• Kyungpook Mathematical Journal
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• v.49 no.2
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• pp.355-387
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• 2009

Functoriality conjecture is one of the central and influential subjects of the present day mathematics. Functoriality is the profound lifting problem formulated by Robert Langlands in the late 1960s in order to establish nonabelian class field theory. In this expository article, I describe the Langlands-Shahidi method, the local and global Langlands conjectures and the converse theorems which are powerful tools for the establishment of functoriality of some important cases, and survey the interesting results related to functoriality conjecture.

• Korean Journal of Mathematics
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• v.31 no.4
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• pp.433-444
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• 2023

Given a function f analytic in open disk centred at origin of radius unity and satisfying the condition |f(z)/g(z) - 1| < 1 for a analytic function g with certain prescribed conditions in the unit disk, radii constants R are determined for the values of Rzf'(Rz)/f(Rz) to lie inside the domain enclosed by the curve |w² - 1| = 1 (lemniscate of Bernoulli). This, in turn, provides a partial solution to the conjectures and problems for determination of sharp bounds R for such functions f.

• Journal of the Korean Mathematical Society
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• v.12 no.1
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• pp.43-50
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• 1975

• Communications of Mathematical Education
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• v.28 no.4
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• pp.529-552
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• 2014

Recently, mathematical reasoning has been considered as one of the most important mathematical thinking abilities to be established in school mathematics. This study is to investigate the mathematical problems on the content of 'Set and Statement' and 'Sequences' in high school according to the four types of reasoning, namely Making Conjectures, Investigating Conjectures, Developing Arguments, and Evaluating Arguments. Those types of reasoning were reconstructed based on Johnson's six types of reasoning suggested in 2010. The content is dealt with in 'Mathematics II' textbook developed and published according to the mathematics curriculum revised in 2009. The subject of this study is nine types of textbooks and mathematical problems in the textbook are consisted of as two parts of 'general problem' and 'evaluation problem'. Finally, the results of this study can be summarized as follow: First, it is stated that students be establishing a logical justification activity, the highest reasoning activity through dealing with the 'Developing Arguments' type of problems affluently in both 'Set and Statement' and 'Sequence' chapters of Mathematics II textbook. Second, it is mentioned that students have an chance to investigate conjectures and develop logical arguments in 'Set and Statement' chapter of Mathematics II textbook. In particular, whereas they have an chance to investigate conjectures and also develop arguments in 'Statement', the 'Set' chapter is given only an opportunity of developing arguments. Third, students are offered on an opportunity of reasoning that can make conjectures and develop logical arguments in 'Sequences' chapter of Mathematics II textbook. Fourth, Mathematics II textbook are geared to do activities that could evaluate arguments while dealing with the problems relevant to 'mathematical process' included in 'general problem'.