Abstract:
The quadratic Büchi surface $B_4$ has affine equations $x_4^2-2x_3^2+x_2^2=x_3^2-2x_2^2+x_1^2=2$. We describe two non-trivial endomorphisms and second-order linear recurrence relations that preserve integrality on $B_4$, thus giving a way to build a forest-like structure on the set of integral points on $B_4$.