Marcellini, Paolo Quasiconvex quadratic forms in two dimensions. (English) Zbl 0567.49007 Appl. Math. Optimization 11, 183-189 (1984). Soient f et g deux formes quadratiques réelles sur \({\mathbb{R}}^ n\). L’auteur donne des conditions pour que f-\(\lambda\) g soit positive définie (resp. semidéfinie). Il retrouve en particulier le fait que si \(n=N=2\), alors, pour une forme quadratique, on a les equivalences: conditions de Legendre-Hadamard \(\Leftrightarrow\) polyconvexité \(\Leftrightarrow\) quasiconvexité. Reviewer: H.Brezis Cited in 22 Documents MSC: 49J45 Methods involving semicontinuity and convergence; relaxation 26B25 Convexity of real functions of several variables, generalizations 15A63 Quadratic and bilinear forms, inner products 90C25 Convex programming Keywords:quadratic forms in two dimensions; Legendre-Hadamard condition; polyconvexity; quasiconvexity PDF BibTeX XML Cite \textit{P. Marcellini}, Appl. Math. Optim. 11, 183--189 (1984; Zbl 0567.49007) Full Text: DOI OpenURL References: [1] Acerbi E, Buttazzo G, Fusco N (to appear) Semicontinuity and relaxation for integrals depending on vector-valued functions. J Math Pures Appl · Zbl 0481.49013 [2] Ball JM (1977) Convexity conditions and existence theorems in nonlinear elasticity. Arch Rat Mech Anal 63:337-403 · Zbl 0368.73040 [3] Ball JM, Currie JC, Olver PJ (1981) Null Lagrangians, weak continuity and variational problems of arbitrary order. J Funct Anal 41:135-175 · Zbl 0459.35020 [4] Bensoussan A, Lions JL, Papanicolaou G (1978) Asymptotic analysis for periodic structures. North-Holland, Amsterdam · Zbl 0404.35001 [5] Dacorogna B (1982) Quasiconvexity and relaxation of nonconvex problems in the calculus of variations. J Funct Anal 46:102-118 · Zbl 0547.49003 [6] Dacorogna B (1982) Weak continuity and weak lower semicontinuity of nonlinear functionals. Lecture Notes in Math 922. Springer-Verlag, Berlin · Zbl 0484.46041 [7] Hadamard J (1905) Sur quelques questions de calcul des variations. Bull Soc Math France 33:73-80 · JFM 36.0430.02 [8] Marcellini P, Sbordone C (1980) Semicontinuity problems in the calculus of variations. Nonlinear Anal 4:241-257 · Zbl 0537.49002 [9] Marcellini P, Sbordone C (1983) On the existence of minima of multiple integrals of the calculus of variations. J Math Pures Appl 62:1-9 · Zbl 0516.49011 [10] Morrey CB (1952) Quasiconvexity and the lower semicontinuity of multiple integrals. Pacific J Math 2:25-53 · Zbl 0046.10803 [11] Morrey CB (1966) Multiple integrals in the calculus of variations. Springer-Verlag, Berlin · Zbl 0142.38701 [12] Murat F (1978) Compacit? par compensation. Ann Sc Norm Sup Pisa 5:489-507 · Zbl 0399.46022 [13] Murat F (1979) Compacit? par compensation II. De Giorgi, Magenes, and Mosco (eds) Proc Inter Meeting Rec Meth Nonlinear Anal. Pitagora, Bologna, pp 245-256 · Zbl 0449.35010 [14] Nirenberg L (1955) Remarks on strongly elliptic partial differential equations. Comm Pure Appl Math 8:648-674 · Zbl 0067.07602 [15] Reshetnyak YG (1968) Stability theorems for mappings with bounded excursion. Sibirskii Math 9:667-684 [16] Serre D (1981) Relations d’ordre entre formes quadratiques en compacit? par compensation. CR Acad Sc Paris 292:785-787 · Zbl 0475.49020 [17] Serre D (1981) Condition de Legendre-Hadamard; espaces de matrices de rang ? 1. C R Acad Sc Paris 293:23-26 · Zbl 0478.49006 [18] Tartar L (1978) Compensated compactness. Heriot-Watt Symposium 4. Pitman, New York [19] Terpstra FJ (1938) Die Darstellung biquadratischer formen als summen von quadraten mit anwendung auf die variations rechnung. Math Ann 116:166-180 · Zbl 0019.35203 This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. It attempts to reflect the references listed in the original paper as accurately as possible without claiming the completeness or perfect precision of the matching.