Alexey Korepanov Title: Strength of strong approximation with a Brownian motion. Abstract: Motion of a particle in Lorentz gas can be strongly (almost surely) approximated by a Brownian motion. Such an approximation implies the functional central limit theorem, the functional law of iterated logarithm, the almost sure central limit theorem and other useful things. A particularly challenging problem in both dynamical systems and probability theory is control of the approximation error. I will present recent new results for dynamical systems such as the doubling map, Axiom A diffeomorphisms, logistic maps or Lorentz gas. Joint work (in progress) with C.Cuny, J.Dedecker and F.Merlevede.