Ha, Phi; Mehrmann, Volker Analysis and reformulation of linear delay differential-algebraic equations. (English) Zbl 1323.34089 Electron. J. Linear Algebra 23, 703-730 (2012). Summary: General linear systems of delay differential-algebraic equations (DDAEs) of arbitrary order are studied in this paper. Under some consistency conditions, it is shown that every linear highorder DAE can be reformulated as an underlying high-order ordinary differential equation (ODE) and that every linear DDAE with single delay can be reformulated as a high-order delay differential equation (DDE). Condensed forms for DDAEs based on the algebraic structure of the system coefficients are derived and these forms are used to reformulate DDAEs as strangeness-free systems, where all constraints are explicitly available. The condensed forms are also used to investigate structural properties of the system like solvability, regularity, consistency and smoothness requirements. Cited in 9 Documents MSC: 34K32 Implicit functional-differential equations 34K06 Linear functional-differential equations Keywords:delay differential-algebraic equation; differential-algebraic equation; regularization; strangeness-index; index reduction Software:Dymola; RODAS PDFBibTeX XMLCite \textit{P. Ha} and \textit{V. Mehrmann}, Electron. J. Linear Algebra 23, 703--730 (2012; Zbl 1323.34089) Full Text: DOI Link Link