It is shown that self-locomotion is possible for a body in Euclidian space, provided its dynamics corresponds to a non-quadratic Hamiltonian, and that the body contains at least 3 particles. The efficiency of the driver of such a system is defined. The existence of an optimal (most efficient) driver is proved.


Let $\left(M,g\right)$ be a complete Riemannian manifold, $\mathrm{\Omega }\subset M$ an open subset whose closure is diffeomorphic to an annulus. If $\partial \mathrm{\Omega }$ is smooth and it satisfies a strong concavity assumption, then it is possible to prove that there are at least two geometrically distinct geodesics in $\overline{\mathrm{\Omega }}=\mathrm{\Omega }\bigcup \partial \mathrm{\Omega }$ starting orthogonally to one connected component of $\partial \mathrm{\Omega }$ and arriving orthogonally onto the other one. The results given in [5] allow to obtain a proof of the existence of two distinct homoclinic orbits for an autonomous Lagrangian system emanating...

In this paper we consider the well-known implicit Lagrange problem: find a trajectory solution of an underdetermined implicit differential equation, satisfying some boundary conditions and which is a minimum of the integral of a Lagrangian. In the tangent bundle of the surrounding manifold X, we define the geometric framework of q-pi- submanifold. This is an extension of the geometric framework of pi- submanifold, defined by Rabier and Rheinboldt for determined implicit differential equations,...

A field of three-component unit vectors on the $2+1$ dimensional spacetime is considered. Two field configurations with different values of the topological charge cannot be connected by the path of field configurations with a finite Euclidean action. Therefore there is no transition between them. The initial and final configurations are assumed to be continuous at infinity. The asymptotic behaviour of intermediate configurations may be arbitrary. The proof is based on the properties of the degree of...

A matrix $A$ in $(max,min)$-algebra (fuzzy matrix) is called weakly robust if $A^k\otimes x$ is an eigenvector of $A$ only if $x$ is an eigenvector of $A$. The weak robustness of fuzzy matrices are studied and its properties are proved. A characterization of the weak robustness of fuzzy matrices is presented and an $O\left(n^2\right)$ algorithm for checking the weak robustness is described.

We study the zero-temperature limit for Gibbs measures associated to Frenkel–Kontorova models on ${\left({ℝ}^d\right)}^{\mathbb{Z}}/{\mathbb{Z}}^d$. We prove that equilibrium states concentrate on configurations of minimal energy, and, in addition, must satisfy a variational principle involving metric entropy and Lyapunov exponents, a bit like in the Ruelle–Pesin inequality. Then we transpose the result to certain continuous-time stationary stochastic processes associated to the viscous Hamilton–Jacobi equation. As the viscosity vanishes, the...

We give a clear and systematic exposition of one-parameter families of brake orbits in dynamical systems on product vector bundles (where the fiber has the same dimension as the base manifold). A generalized definition of a brake orbit is given, and the relationship between brake orbits and periodic orbits is discussed. The brake equation, which implicitly encodes information about the brake orbits of a dynamical system, is defined. Using the brake equation, a one-parameter family of brake orbits...

Nous étudions les aspects infinitésimaux du problème suivant. Soit $H$ un hamiltonien de ${ℝ}^{2n}$ dont la surface d’énergie $\{H=1\}$ borde un domaine compact et étoilé de volume identique à celui de la boule unité de ${ℝ}^{2n}$. La surface d’énergie $\{H=1\}$ contient-elle une orbite périodique du système hamiltonien$$\left\{\begin{array}{cc}\dot{q}\hfill & =\frac{\partial H}{\partial p}\hfill \\ \dot{p}\hfill & =-\frac{\partial H}{\partial q}\hfill \end{array}\right.$$dont l’action soit au plus $\pi$ ?