二步幂零李群上—类左不变微分算子亚椭圆的充要条件
郑驻军, 段一士
A SUFFICIENT AND NECESSARY CONDITION FOR HYPOELLIPTICITY OF A CLASS OF LEFT INVARIANT DIFFERENTIAL OPERATORS ON TWO STEP STRATIFIED NILPOTENT LIE GROUP
Zhu Jun ZHENG, Yi Shi DUAN
应用数学学报
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1999, (3): 321
-326
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DOI: 10.12387/C1999056