Let A = M N E IR nn be a splitting. We investigate the spectral properties of the iteration matrix M 1 N by considering the relationships of the graphs of A, M, N, and M1 N. We call a splitting an M-splitting if M is a nonsingular M-matrix and N;;. O. For an M-splitting of an irreducible Z-matrix A we prove that the circuit index of M1 N is the greatest common divisor of certain sets of integer...

All rings are commutative with identity and all modules are unital. Let R be a ring, M an R-module and R (M), the idealization of M . Homogeneous ideals of R (M) have the form I (+)N where I is an ideal of R, N a submodule of M and IM ⊆ N . The purpose of this paper is to investigate how properties of a homogeneous ideal I (+)N of R (M) are related to those of I and N . We show that if M is a m...

let $r$ be a ring and $m$ a right $r$-module with $s=end_r(m)$. a module $m$ is called semi-projective if for any epimorphism $f:mrightarrow n$, where $n$ is a submodule of $m$, and for any homomorphism $g: mrightarrow n$, there exists $h:mrightarrow m$ such that $fh=g$. in this paper, we study sgq-projective and$pi$-semi-projective modules as two generalizations of semi-projective modules. a m...

This paper provide a generalization of non-reducible descriptors. Non-reducible descriptors are used in supervised pattern recognition problems when the pattern descriptions consist of Boolean variables. This generalization extends the concept of distance between patterns of different classes. A mathematical model to construct generalized non-reducible descriptors, a computational procedure, an...

it is called nontrivial if {0} 6= J 6= X. This notion was introduced by Alfsen and Effros [1] and has proved useful in Banach space geometry, approximation theory and harmonic analysis; see [12] for a detailed account. A number of authors have studied the M -ideal structure in L(X), the space of bounded linear operators on a Banach space X, with special emphasis on the question whether K(X), th...

We study the family of rational sets of words, called completely reducible and which are such that the syntactic representation of their characteristic series is completely reducible. This family contains, by a result of Reutenauer, the submonoids generated by bifix codes and, by a result of Berstel and Reutenauer, the cyclic sets. We study the closure properties of this family. We prove a resu...