# Volume 15 (2007): Issue 1 (January 2007)

Journal Details
Format
Journal
eISSN
1898-9934
ISSN
1426-2630
First Published
09 Jun 2008
Publication timeframe
4 times per year
Languages
English

0 Articles
Open Access

#### Several Classes of BCI-algebras and their Properties

Published Online: 13 Jun 2008
Page range: 1 - 9

#### Abstract

I have formalized the BCI-algebras closely following the book [6], sections 1.1 to 1.3, 1.6, 2.1 to 2.3, and 2.7. In this article the general theory of BCI-algebras and several classes of BCI-algebras are given. MML identifier: BCIALG 1 , version: 7.8.04 4.81.962

Open Access

#### Formal Languages - Concatenation and Closure

Published Online: 13 Jun 2008
Page range: 11 - 15

#### Abstract

Formal languages are introduced as subsets of the set of all 0-based finite sequences over a given set (the alphabet). Concatenation, the n -th power and closure are defined and their properties are shown. Finally, it is shown that the closure of the alphabet (understood here as the language of words of length 1) equals to the set of all words over that alphabet, and that the alphabet is the minimal set with this property. Notation and terminology were taken from [5] and [13]. MML identifier: FLANG 1 , version: 7.8.04 4.81.962

Open Access

#### Basic Properties of Determinants of Square Matrices over a Field1

Published Online: 13 Jun 2008
Page range: 17 - 25

#### Abstract

In this paper I present basic properties of the determinant of square matrices over a field and selected properties of the sign of a permutation. First, I define the sign of a permutation by the requirement where p is any fixed permutation of a set with n elements. I prove that the sign of a product of two permutations is the same as the product of their signs and show the relation between signs and parity of permutations. Then I consider the determinant of a linear combination of lines, the determinant of a matrix with permutated lines and the determinant of a matrix with a repeated line. Finally, at the end I prove that the determinant of a product of two square matrices is equal to the product of their determinants. MML identifier: MATRIX11 , version: 7.8.04 4.81.962