The work on almost block diagonal linear systems led to cooperation with Andreas Karageorghis. Our research is concentrated on the high performance solution of structured linear systems arising from spectral approximations on conforming and non-conforming domain decompositions. Results have been summarized in the following publications:

+ "Conditioning of Pseudospectral Matrices for Certain Domain Decompositions," with A. Karageorghis, International Journal of Scientific Computing, Vol. 14, No. 1, 1999, 107-119

+ "Direct Methods for Spectral Approximations in Non-conforming Domain Decompositions," with A. Karageorghis, Journal of Computers in Mathematics Applications, 35(11), 1998, 75-82

+ "High Performance Solution of Linear Systems Arising from Conforming Spectral Approximations for Non-conforming Domain Decompositions," with A. Karageorghis, in: L. Vulkov et. al. (eds.), Proceedings of the 1st Workshop on Numerical Analysis and Applications, Lecture Notes in Computer Science 1196, Springer-Verlag, Berlin, 1997, 373-379

+ "High Performance Solution of Linear Systems Arising in Spectral Domain Decomposition Techniques," with C. Cyphers and A. Karageorghis, in: A. Dishlev (ed.), Invited Lectures and Short Communications Delivered at the 6th International Colloquium on Differential Equations, Impulse-M, Sofia, Bulgaria, 1996, 203-212

+ "An Efficient Direct Method for Fully Conforming Spectral Collocation Schemes," with A. Karageorghis, Numerical Algorithms, 12, 1996, 309-319

+ "High Performance Solution of Partial Differential Equations Discretized Using a Chebyshev Spectral Collocation Method," with C. Cyphers and A. Karageorghis, Journal of Computational and Applied Mathematics, 66(1), 1996, 71-80