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机译:SYSTEMS OF SEMILINEAR WAVE EQUATIONS WITH MULTIPLE SPEEDS IN TWO SPACE DIMENSIONS AND A WEAKER NULL CONDITION
Department of Mathematics, Graduate School of Science, Osaka University 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan;
Semilinear wave equation; null condition; weak null condition; global existence; asymptotic behavior; multiple propagation speeds;