A maximum principle for weakly coupled systems of second order partial differential equations with nonnegative characteristic form

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The maximum principle of Fichera for a single second order partial differential equation with nonnegative characteristic form is extended to weakly coupled linear systems of such equations. A Phragmén-Lindelöf principle for such systems, giving conditions for the maximum principle to hold in unbounded domains, is proved. Comparison theorems for degenerate parabolic semilinear systems in bounded and unbounded domains are also proved.

Original languageEnglish (US)
Pages (from-to)59-74
Number of pages16
JournalRocky Mountain Journal of Mathematics
Issue number1
StatePublished - Jan 1 1981


ASJC Scopus subject areas

  • Mathematics(all)

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