Generalized Perron Roots and Solvability of the Absolute Value Equation
Abstract
Let $A$ be a $n\times n$ real matrix. The piecewise linear equation system $z-A\vert z\vert =b$ is called an absolute value equation (AVE). It is well-known to be equivalent to the linear complementarity problem. Unique solvability of the AVE is known to be characterized in terms of a generalized Perron root called the sign-real spectral radius of $A$. For mere, possibly non-unique, solvability no such characterization exists. We narrow this gap in the theory. That is, we define the concept of the aligned spectrum of $A$ and prove, under some mild genericity assumptions on $A$, that the mapping degree of the piecewise linear function $F_A:\mathbb{R}^n\to\mathbb{R}^n\,, z\mapsto z-A\lvert z\rvert$ is congruent to $(k+1)\mod 2$, where $k$ is the number of aligned values of $A$ which are larger than $1$. We also derive an exact--but more technical--formula for the degree of $F_A$ in terms of the aligned spectrum. Finally, we derive the analogous quantities and results for the LCP.
- Publication:
-
arXiv e-prints
- Pub Date:
- December 2019
- DOI:
- 10.48550/arXiv.1912.08157
- arXiv:
- arXiv:1912.08157
- Bibcode:
- 2019arXiv191208157R
- Keywords:
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- Mathematics - Optimization and Control;
- Mathematics - Numerical Analysis;
- 65K99;
- 90C33;
- 15A24
- E-Print:
- 20 pages, 2 figures