5 papers
On formal concepts of random formal contexts
Taro Sakurai
In formal concept analysis, it is well-known that the number of formal concepts can be exponential in the worst case. To analyze the average case, we introduce a probabilistic mode…
Finite groups with very few character values
Taro Sakurai
Finite groups with very few character values are characterized. The following is the main result of this article: a finite non-abelian group has precisely four character values if…
The isomorphism problem for group algebras: a criterion
Taro Sakurai
Let be a finite unital commutative ring. We introduce a new class of finite groups, which we call hereditary groups over . Our main result states that if is a hereditary…
An explicit formula for a weight enumerator of linear-congruence codes
Taro Sakurai
An explicit formula for a weight enumerator of linear-congruence codes is provided. This extends the work of Bibak and Milenkovic [IEEE ISIT (2018) 431-435] addressing the binary c…
On theorems of Brauer-Nesbitt and Brandt for characterizations of small block algebras
Shigeo Koshitani, Taro Sakurai
In 1941, Brauer-Nesbitt established a characterization of a block with trivial defect group as a block with where is the number of irreducible ordinary charac…