## Analyticity for singular sums of squares of degenerate vector fields

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- by David S. Tartakoff PDF
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**134**(2006), 3343-3352 Request permission

## Abstract:

Recently J. J. Kohn (2005) proved $C^\infty$ hypoellipticity for \[ P_k=L\overline {L} + \overline {L}|z|^{2k}L =-\overline {L}^*\overline {L} - (\overline {z}^kL)^*\overline {z}^kL\mathrm { \quad with \quad } L={\partial \over \partial z} + i\overline {z}{\partial \over \partial t},\] (the negative of) a singular sum of squares of complex vector fields on the complex Heisenberg group, an operator which exhibits a*loss*of ${k-1}$ derivatives. Subsequently, M. Derridj and D. S. Tartakoff proved analytic hypoellipticity for this operator using rather different methods going back to earlier methods of Tartakoff. Those methods also provide an alternate proof of the hypoellipticity given by Kohn. In this paper, we consider the equation \[ P_{m,k}=L_m\overline {L_m} + \overline {L_m} |z|^{2k}L_m \mathrm { \; with \;} L_m={\partial \over \partial z} + i\overline {z}|z|^{2m}{\partial \over \partial t},\] for which the underlying manifold is only of finite type, and prove analytic hypoellipticity using methods of Derridj and Tartakoff. This operator is also subelliptic with large loss of derivatives, but the exact loss plays no role for analytic hypoellipticity. Nonetheless, these methods give a proof of $C^\infty$ hypoellipticity with precise loss as well, which is to appear in a forthcoming paper by A. Bove, M. Derridj, J. J. Kohn and the author.

## References

- A. Bove, M. Derridj, J.J. Kohn and D.S. Tartakoff,
*Hypoellipticity for a sum of squares of complex vector fields with large loss of derivatives,*preprint. - A. Bove and D.S. Tartakoff,
*Analytic hypo-ellipticity at non-symplectic characteristics when the symplectic form changes its rank,*preprint. - M Christ,
*A remark on sums of squares of complex vector fields,*preprint, arXiv:math.CV/0503506. - Makhlouf Derridj and David S. Tartakoff,
*Local analyticity for $\square _b$ and the $\overline \partial$-Neumann problem at certain weakly pseudoconvex points*, Comm. Partial Differential Equations**13**(1988), no. 12, 1521–1600. MR**970155**, DOI 10.1080/03605308808820586 - M. Derridj and D.S. Tartakoff,
*Analyticity and loss of derivatives,*Annals of Mathematics**162(2)**(2005), as Appendix to*Hypoellipticity and loss of derivatives,*by J. J. Kohn in the same issue. - F. Hirzebruch,
*Topological methods in algebraic geometry*, Third enlarged edition, Die Grundlehren der mathematischen Wissenschaften, Band 131, Springer-Verlag New York, Inc., New York, 1966. New appendix and translation from the second German edition by R. L. E. Schwarzenberger, with an additional section by A. Borel. MR**0202713** - J.J. Kohn,
*Hypoellipticity and loss of derivatives,*Annals of Mathematics**162(2)**(2005). - C. Parenti and A. Parmeggiani,
*A Note on Kohn’s and Christ’s Examples,*preprint. - Yum-Tong Siu,
*Extension of twisted pluricanonical sections with plurisubharmonic weight and invariance of semipositively twisted plurigenera for manifolds not necessarily of general type*, Complex geometry (Göttingen, 2000) Springer, Berlin, 2002, pp. 223–277. MR**1922108** - David S. Tartakoff,
*Local analytic hypoellipticity for $\square _{b}$ on nondegenerate Cauchy-Riemann manifolds*, Proc. Nat. Acad. Sci. U.S.A.**75**(1978), no. 7, 3027–3028. MR**499657**, DOI 10.1073/pnas.75.7.3027 - David S. Tartakoff,
*The local real analyticity of solutions to $\square _{b}$ and the $\bar \partial$-Neumann problem*, Acta Math.**145**(1980), no. 3-4, 177–204. MR**590289**, DOI 10.1007/BF02414189 - François Trèves,
*Analytic hypo-ellipticity of a class of pseudodifferential operators with double characteristics and applications to the $\overline \partial$-Neumann problem*, Comm. Partial Differential Equations**3**(1978), no. 6-7, 475–642. MR**492802**, DOI 10.1080/03605307808820074

## Additional Information

**David S. Tartakoff**- Affiliation: Department of Mathematics, University of Illinois at Chicago, m/c 249, 851 S. Morgan Street, Chicago, Illinois 60607
- Email: dst@uic.edu
- Received by editor(s): June 1, 2005
- Published electronically: May 12, 2006
- Communicated by: Eric Bedford
- © Copyright 2006
American Mathematical Society

The copyright for this article reverts to public domain 28 years after publication. - Journal: Proc. Amer. Math. Soc.
**134**(2006), 3343-3352 - MSC (2000): Primary 35H10; Secondary 35N15
- DOI: https://doi.org/10.1090/S0002-9939-06-08419-X
- MathSciNet review: 2231919