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Author(s): 

VALIZADEH M. | Tadayon m.h.

Issue Info: 
  • Year: 

    2021
  • Volume: 

    15
  • Issue: 

    1
  • Pages: 

    41-60
Measures: 
  • Citations: 

    0
  • Views: 

    35
  • Downloads: 

    16
Abstract: 

Let G be a digraph with positive edge weights as well as s and t be two vertices of G. The marking problem (MP) states how to mark some edges of G with T and F, where every path starting at source s will reach target t and the total weight of the marked edges is minimal. When traversing the digraph, T-marked edges should be followed while Fmarked edges should not. The basic applications and properties of the marking problem have been investigated in [1]. This paper provides new contributions to the marking problem as follows: (i) the MP is NP-Complete even if the underlying digraph is an unweighted binary DAG,(ii) the MP cannot be approximated within α,logn in an unweighted DAG with n vertices and even in an unweighted binary DAG. Furthermore, a lower bound to the optimal solution of the MP is provided. We also study the complexity and challenges of the marking problem in program flow graphs.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

View 35

مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic ResourcesDownload 16 مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic ResourcesCitation 0 مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic ResourcesRefrence 0
Issue Info: 
  • Year: 

    2024
  • Volume: 

    9
  • Issue: 

    2
  • Pages: 

    176-183
Measures: 
  • Citations: 

    0
  • Views: 

    0
  • Downloads: 

    0
Abstract: 

In this paper, we investigate the real roots of a special class of square matrices, leveraging the properties of involutory and idempotent matrices. We focus on determining real roots for real orthogonal and symmetric matrices, demonstrating how involutory matrices facilitate this process. Our results show that a real involutory matrix of order $n$ with a positive determinant always admits a real root. Furthermore, for real symmetric matrices, we establish that a real root exists if every negative eigenvalue appears with even multiplicity. We also explore the structure of idempotent matrices, presenting a general block form derived through similarity transformations. Specifically, we prove that for invertible submatrices $A$ and $D$, along with arbitrary block matrices $B$ and $C$, a constructed matrix $P$ exhibits idempotency. An illustrative example is provided to clarify this construction, highlighting its application in generating idempotent and involutory matrices from simpler components. Additionally, we examine the root-Approximability of orthogonal matrices, showing that certain sequences of matrices converge to the identity while their powers approximate the original matrix. This work extends existing results on matrix functions and diagonalization, offering practical insights into the analysis and computation of matrix roots. Our findings contribute to the broader understanding of matrix theory, with potential applications in numerical linear algebra and functional analysis.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

View 0

مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic ResourcesDownload 0 مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic ResourcesCitation 0 مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic ResourcesRefrence 0
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