Strong stability for LTI system with multi-delays

Strong delay-independent stability of MD-LTI(Linear Time Invariant with Multi-Delays) system
$\dot{x}(t)=A_{1} x(t)+\sum\limits_{i=2}^{N} A_{i} x(t-\tau_{i})$
, has attracted much attention, and some encouraging results have been obtained when
$\mathrm{N}<=2$
. However, it is complicated even infeasible to use the LMI (linear matrix inequality) to analysis(analyze) the stability of MD-LTI when
$\mathrm{N}> 2$
. In the paper, a quadric form based on Lyapunov matrix algebraic equation (or inequality) method for the necessary and sufficient condition of MD-LTI under the case of N>2 is proposed. Three criteria are obtained, and three numerical examples are given to illustrate the proposed method results.