Abstract
In this paper we prove two results on the Levi conditions for weakly hyperbolic systems with characteristics of constant multiplicities. A first result concerns scalar operators: we prove that Levi conditions defined by the second author in [29] are equivalent to the usual Levi conditions for scalar operator. A second result concerns systems whose principal symbol has a Jordan form made of a large number of $2 \times 2$ blocks. For these systems we express the first Levi condition via an invariant constructed from the sub-characteristic matrix. Moreover we show that this condition is necessary for the $C^\infty$ well-posedness.
Citation
Giovanni TAGLIALATELA. Jean VAILLANT. "Remarks on the Levi conditions for differential systems." Hokkaido Math. J. 37 (3) 463 - 492, August 2008. https://doi.org/10.14492/hokmj/1253539531
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