• 대한수학회보
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• 제42권3호
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• pp.453-467
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• 2005

Let K be an algebraic number field. If k is the maximal cyclotomic subextension in K then the Schur K-group S(K) is obtained from the Schur k-group S(k) by scalar extension. In the paper we study projective Schur group PS(K) which is a generalization of Schur group, and prove that a projective Schur K-algebra is obtained by scalar extension of a projective Schur k-algebra where k is the maximal radical extension in K with mild condition.

• 대한수학회논문집
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• 제10권3호
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• pp.527-539
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• 1995

We consider the Schur groups of some module categories, which are subcategories of category of divisorial modules over a Krull domain. Then we obtain the exact sequence connecting class group, Schur class group and Schur groups of these categories.

• 대한수학회지
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• 제39권1호
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• pp.1-11
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• 2002

A Schur algebra was generalized to projective Schur algebra by admitting twisted group algebra. A Schur algebra is a projective Schur algebra with trivial 2-cocycle. In this paper we study situations that Schur algebra is a projective Schur algebra with nontrivial cocycle, and we find a criterion for a projective Schur algebra to be a Schur algebra.

• 대한수학회보
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• 제51권6호
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• pp.1689-1696
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• 2014

Recently, it was proved that every p-Schur ring over an abelian group of order $p^3$ is Schurian. In this paper, we prove that every commutative p-Schur ring over a non-abelian group of order $p^3$ is Schurian.

• 한국수학사학회지
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• 제19권2호
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• pp.125-140
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• 2006

군환의 특별한 부분환으로 정의된 수어환(Schur ring)은 치환군의 구조 연구를 위해 1933년 I.Schur에 의해 소개되었다. 그 후 30여 년 동안 군론과 표현론에서 응용되던 수어환은 1970년대에 이르러 획기적인 분기점을 맞이하게 된다. 조합론, 특별히 대수적 그래프에 관한 많은 연구 속에서, 그래프를 분류하기위해 수어환을 이용하려는 새로운 시도가 Klin과 Poschel에 의해 제안되었다. 이것은 당시 대수학에서 이룩해낸 유한단순군의 분류에 큰 도움을 받은 것이다. 이 논문에서는 수어환의 발생에 대한 역사적 배경과, 수어환이 군이론에서 어떻게 이용되었는지를 살펴보고, 또한 그래프이론에서의 역할을 조사한다.

• 대한수학회보
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• 제38권4호
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• pp.803-814
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• 2001

A projective Schur algebra associated with a partition of finite group G can be constructed explicitly by defining linear transformations of G. We will consider various linear transformations and count the number of equivalent classes in a finite group. Then we construct projective Schur algebra dimension is determined by the number of classes.

• 대한수학회보
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• 제35권3호
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• pp.527-532
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• 1998

We study some properties of Schur functor and its sub-functions related to separable algebras and cyclotomic algebras.

• 대한수학회지
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• 제38권1호
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• pp.77-85
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• 2001

If an Azumaya algebra A is a homomorphic image of a finite group ring RG where G is a direct product of subgroups then A can be decomposed into subalgebras A(sub)i which are homomorphic images of subgroup rings of RG. This result is extended to projective Schur algebras, and in this case behaviors of 2-cocycles will play major role. Moreover considering the situation that A is represented by Azumaya group ring RG, we study relationships between the representing groups for A and A(sub)i.

• Journal of applied mathematics & informatics
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• 제16권1_2호
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• pp.303-306
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• 2004

There are 49 non-metacyclic p-groups of order less than 1000 with trivial Schur multiplier. In this paper we give a list of deficiency zero presentations for these groups.

• 대한수학회논문집
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• 제20권1호
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• pp.35-49
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• 2005

For an extension field K of k, a restriction homomorphism on Brauer k-group B(k) maps Brauer k-algebras to Brauer K- algebras by tensor product. A purpose of this work is to study the restriction map that sends radical (Schur) k-algebras to radical (Schur) K-algebras. And we ask an analogous question with respect to corestriction map on Brauer group B(K) that whether the corestriction map sends radical K-algebras to radical k-algebras.