Results 41 to 50 of about 51,079 (125)
, 2006 We consider an operator $ P $ which is a sum of squares of vector fields with analytic coefficients. The operator has a non-symplectic characteristic manifold, but the rank of the symplectic form $ $ is not constant on $ \Char P $. Moreover the Hamilton foliation of the non symplectic stratum of the Poisson-Treves stratification for $ P $ consists of
Bove, Antonio, Tartakoff, David S.
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Sums of squares of complex vector fields and (analytic-) hypoellipticity [PDF]
Mathematical Research Letters, 2006 BOVE, ANTONIO +3 more
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On Li-Yau gradient estimate for sum of squares of vector fields up to higher step
, 2016 41 ...
Chang, Der-Chen +2 more
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Journal of Differential Equations, 1998 This paper deals with the global solvability on the torus for some classes of second order partial differential operators \(P\) having the form of sum of squares of real vector fields. It is proved in Theorem 1.7 that \(P\) is solvable if and only if an algebraic condition involving irrational non-Liouville numbers holds.
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Mapping the visual cortex with Zebra noise and wavelets. [PDF]
J VisSkriabine S +4 more
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A Review: Construction of Statistical Distributions. [PDF]
Entropy (Basel)Fang KT, Lin YX, Deng YH.
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Computational Strategy for Analyzing Effective Properties of Random Composites-Part II: Elasticity. [PDF]
Materials (Basel)Czapla R +4 more
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On the eigenvalues of the operator sum of squares of vector fields
Chinese Science Bulletin, 1998 Xuebo Luo, Pengcheng Niu
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