Lipschitz geometry of pairs of normally embedded Hölder triangles

Abstract: We consider a special case of the outer bi-Lipschitz classification of real semialgebraic (or, more general, definable in a polynomially bounded o-minimal structure) surface germs, obtained as a union of two normally embedded H\"older triangles. We define a combinatorial invariant of an equivalence class of such surface germs, called $\sigma\tau$-pizza, and conjecture that, in this special case, it is a complete combinatorial invariant of outer bi-Lipschitz equivalence.