Tillings

• Jean-Claude Yakoubsohn

Look at the picture ;-)

Sequences, differential equations and billiards

• Xavier Buff

I will present a joint work with Jasmin Raissy. In particular, I will show how the study of sequences of complex numbers satisfying the recursion $(x_{n+1},y_{n+1})=(x_n+y_n^2,y_n+x_n^2)$ which is the step-$1$ Euler's method of the differential equation $(x^{\prime },y^{\prime })=(y^2,x^2)$ relates to the study of trajectories in a equilateral triangular billiard.