We present a way to derive a priori estimates in ${L}^{\infty}$ for a class of quasilinear systems containing examples with a leading part which is neither diagonal nor of Uhlenbeck type. Moreover, a perturbation term with natural growth in first order derivatives is allowed.

@article{ASNSP_2009_5_8_3_417_0, author = {Kr\"omer, Stefan}, title = {A priori estimates in L$^{\infty }$ for non-diagonal perturbed quasilinear systems}, journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze}, publisher = {Scuola Normale Superiore, Pisa}, volume = {Ser. 5, 8}, number = {3}, year = {2009}, pages = {417-428}, zbl = {1181.35064}, mrnumber = {2581428}, language = {en}, url = {http://www.numdam.org/item/ASNSP_2009_5_8_3_417_0} }

Krömer, Stefan. A priori estimates in L$^{\infty }$ for non-diagonal perturbed quasilinear systems. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Serie 5, Volume 8 (2009) no. 3, pp. 417-428. http://www.numdam.org/item/ASNSP_2009_5_8_3_417_0/

[1] On a nonlinear partial differential equation having natural growth terms and unbounded solution, Ann. Inst. H. Poincaré, Anal. Non Linéaire 5 (1988), 347–364. | Numdam | MR 963104 | Zbl 0696.35042

, and ,[2] Nonlinear systems of elliptic equations with natural growth conditions and sign conditions, Appl. Math. Optim. 46 (2002), 143–166. | MR 1944757 | Zbl 1077.35046

and ,[3] Quasi-monotonicity and perturbated systems with critical growth, Indiana Univ. Math. J. 41 (1992), 483–504. | MR 1183355 | Zbl 0799.35075

and ,[4] “Quasilinear Elliptic Equations with Degenerations and Singularities”, de Gruyter Series in Nonlinear Analysis and Applications, Vol. 5, Walter de Gruyter, Berlin, 1997. | MR 1460729

, and ,[5] “Measure Theory and Fine Properties of Functions”, Studies in Advanced Mathematics, CRC Press, Boca Raton, 1992. | MR 1158660 | Zbl 0804.28001

and ,[6] “Weak Convergence Methods for Nonlinear Partial Differential Equations”, Regional conference series in mathematics, Vol. 74, AMS, Providence, RI, 1990. | MR 1034481

,[7] A note on the Hölder continuity of solutions of variational problems, Abh. Math. Sem. Univ. Hamburg 43 (1975), 59–63. | MR 377648 | Zbl 0316.49008

,[8] “Multiple Integrals in the Calculus of Variations and Nonlinear Elliptic Systems”, Annals of Mathematics Studies, Vol. 105, Princeton University Press, Princeton, New Jersey, 1983. | MR 717034 | Zbl 0516.49003

,[9] Branches of positive solutions of quasilinear elliptic equations on non–smooth domains, Nonlinear Anal. 64 (2006), 2183–2202. | MR 2213897 | Zbl 1189.35112

and ,[10] “Linear and Quasilinear Elliptic Equations”, Mathematics in Science and Engineering, Vol. 46, Academic Press, New York-London, 1968. | MR 244627 | Zbl 0164.13002

and ,[11] On the existence of weak solutions of perturbed systems with critical growth, J. Reine Angew. Math. 393 (1989), 21–38. | MR 972359 | Zbl 0664.35027

,[12] Solvability of perturbed elliptic equations with critical growth exponent for the gradient, J. Math. Anal. Appl. 139 (1989), 63–77. | MR 991927 | Zbl 0691.35038

,[13] On the angle condition for the perturbation of elliptic systems, Ann. Scuola Norm. Sup. Pisa Cl. Sci. (4) 29 (2000), 253–268. | Numdam | MR 1784175 | Zbl 0961.35042

,[14] Testfunctions for elliptic systems and maximum principles, Forum Math. 12 (2000), 23–52. | MR 1736096 | Zbl 0942.35065

,[15] On the regularity of weak solutions of certain elliptic systems, Calc. Var. Partial Differential Equations 25 (2006), 247–255. | MR 2188748 | Zbl 1331.35123

[16] Unbounded critical points for a class of lower semicontinuous functionals, J. Differential Equations 201(2004), 25–62. | MR 2057537 | Zbl 1330.35103

and ,[17] Existence, multiplicity, perturbation, and concentration results for a class of quasi-linear elliptic problems, Electron. J. Differ. Equ., Monogr. 7 (electronic), 2006. | MR 2224538 | Zbl 1293.35093

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