  ![On the right: the linear model of $[T_P,P,F_P{\bigr\rvert_{P}}]$, the map being affine on each of the intervals $B_0,\ldots, B_k$ (picture is for $k=0$). On the left: its Markov graph.[]{data-label="fig:model-Fk"}](periods-sigma-fig00){width="00.00000%"}  ![On the right: the linear model of $[T_P,P,F_P{\bigr\rvert_{P}}]$, the map being affine on each of the intervals $B_0,\ldots, B_k$ (picture is for $k=0$). On the left: its Markov graph.[]{data-label="fig:model-Fk"}](periods-sigma-fig00){width="00.00000%"}  