• Journal for History of Mathematics
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• v.25 no.4
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• pp.69-82
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• 2012

The objective of this paper is to study De Morgan's perspective on teaching and learning complex numbers. De Morgan's didactical approaches reflect the process of development of his thoughts about algebra from universal arithmetic, symbolic algebra to meaning algebra. De Morgan develop his perspective on algebra by justifying and explaining complex numbers. This implies that teaching and learning complex numbers is a catalyst for mathematical development of De Morgan.

• Journal for History of Mathematics
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• v.17 no.2
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• pp.73-84
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• 2004

Stone introduced extremally disconnected spaces as the image of complete Boolean algebras under his famous duality between Bool and ZComp and they turn out to be projective objects in various categories of Hausdorff spaces and completely regular ones are exactly those X with Dedekind complete C(X, ). In the pointfree setting, extremally disconnected frame (= De Morgan frame) are those with De Morgan condition. In this paper, we investigate a historical aspect of De Morgan frame together with that of De Morgan.

• School Mathematics
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• v.10 no.4
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• pp.557-571
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• 2008

The objective of this paper is to study De Morgan's thoughts on teaching and learning negative numbers. We studied De Morgan's point of view on negative numbers, and analyzed his didactical approaches for negative numbers. De Morgan make students explore impossible subtractions, investigate the rule of the impossible subtractions, and construct the signification of the impossible subtractions in succession. In De Morgan' approach, teaching and learning negative numbers are connected with that of linear equations, the signs of impossible subtractions are used, and the concept of negative numbers is developed gradually following the historic genesis of negative numbers. Also, we analyzed the strengths and weaknesses of the De Morgan's approaches compared with the mathematics curriculum.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.531-536
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• 1998

It is well known that a Boolean algebra is one of the most important algebra for engineering. A fuzzy algebra, which is referred to also as a Kleen algebra, is obtained from a Boolean algebra by replacing the complementary law in the axioms of a Bloolean algebra with the Kleen's law, where the Kleen's law is a weaker condition than the complementary law. Removal of the Kleen's law from a Kleen algebra gives a De Morgan algebra. In this paper, we generate lattice structures of the above related algebraic systems having finite elements by using a computer. From the result, we could find out a hypothesis that the structure excepting for each element name between a Kleene algebra and a De Morgan algebra is the same from the lattice standpoint.

• Journal for History of Mathematics
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• v.20 no.4
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• pp.175-190
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• 2007

In the nineteenth century was Augustus De Morgan, British mathematician, a great mathematics teacher. Although his name is well known to everybody who is interested in set theory, his major mathematical legacy would arise from his novel research in logic. In this article, we first investigate De Morgan's life briefly; we then consider his precious philosophy of mathematics education based on his students' remarks and his works. Finally, by considering his teaching style, we highlight some of the ingredients that go into making a great mathematics teacher.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.2
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• pp.51-59
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• 2010

Two logic transformations, De Morgan and re-substitution, are sufficient to convert a unate gate network (UGN) to a more general balanced inversion parity (BIP) network. Circuit classes of interest are discussed in detail. We prove that De Morgan and re-substitution transformations are test-set preserving for path delay faults. Using the results of this paper, we can easily show that a high-level test set for a function z that detects all path delay faults in any UGN realizing z also detects all path delay faults in any BIP realization of z.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.522-525
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• 1998

Although each de Morgan algebra has not always fixed points(centers), it has always fixed cores, the natural extention of fixed points. Fixed cores, of they do not degenerate to fixed points, are Boolean algebras, It is also shown the necessary and sufficient condition a algebra to be a Kleene algebra(fuzzy algebra) is that it has just one fixed core.

• Journal for History of Mathematics
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• v.22 no.4
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• pp.129-144
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• 2009

The purpose of this study is what exactly De Morgan contributed to abstract algebra and mathematical logic. He recognised the purely symbolic nature of algebra and was aware of the existence of algebras other than ordinary algebra. He madealgebra as a science by introducing the ordered field and made the base for abstract algebra. He was one of the reformer of classical mathematical logic. Looking into De Morgan's works, we made it clear that the developments of algebra and mathematical logic in 19C.

• Journal for History of Mathematics
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• v.21 no.4
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• pp.61-78
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• 2008

In this paper, we discuss about De Morgan's view on the development of algebra according to following distinctions: arithmetic, universal arithmetic, symbolic algebra, significant algebra. De Morgan thought that the differences between arithmetic and universal arithmetic lie in the usage of letters and the immediate performance of computation. In his viewpoint, universal arithmetic is a transitional phase, in which absurd phenomena occur, from arithmetic to algebra and these absurd phenomena call for algebra. The feature of De Morgan's view on the development of algebra is that symbolic calculus which consist of symbol system without symbol's meaning is acquired, then as extended meanings are furnished to symbols, symbolic calculus become logical so significant calculus is developed. For example, Single algebra is developed, as an extended meaning is furnished to a symbol -1, and double algebra is developed, as an extended meaning is furnished to a symbol $\sqrt{-1}$. According to De Morgan, a symbol system is derived from the incompleteness of a prior symbol system.

• 전기의세계
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• v.28 no.8
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• pp.57-65
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• 1979

This paper is concerned with not only the transformation of the logic diagrams to the NAND and the NOR forms but also the inverse transformation deriving the simple Boolean function from a logic diagram. The conversions of the algebraic expression from the AND, OR and NOT operations to the NAND and the NOR operations are usually quite complicated, because they involve a large number of repeated applications of De Morgan's Theorem and the other logic relations. For the derivation of the Boolean function, it becomes difficult because the Boolean function is determined from the De Morgan's theorem in consecutive order until the output is expressed in terms of input variables (9). But, these difficulties are avoided by the use of new techniques, called the TWO-NOTs method and the MOVING-NOT method, that are presented in this paper.