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An isotypic Kronecker web is a family of corank m foliations ${\left\{{ℱ}_t\right\}}_{t\in ℝP^1}$ such that the curve of annihilators t ↦ (T x F t)⊥ ∈ Grm(T x* M) is a rational normal curve in the Grassmannian Grm(T x*M) at any point x ∈ M. For m = 1 we get Veronese webs introduced by I. Gelfand and I. Zakharevich [Gelfand I.M., Zakharevich I., Webs, Veronese curves, and bi-Hamiltonian systems, J. Funct. Anal., 1991, 99(1), 150–178]. In the present paper, we consider the problem of local classification of isotypic Kronecker webs...

We consider different convexity notions for functions $F:{ℝ}^{2\times 2}\to ℝ$. We give a new characterisation of polyconvexity and a sufficient condition for quasiconvexity.