André's motivic formulation of the Grothendieck period conjecture

Let $X$ be a pure or mixed motive defined over $\overline{\mathbb{Q}}$. Write $\mathrm{periods}(X)$ for its periods and $\mathcal{G}_{\mathrm{mot}}(X)$ for its motivic Galois group. Grothendieck period conjecture.

$$\operatorname{tr.deg}_{\mathbb{Q}}\,\overline{\mathbb{Q}}(\mathrm{periods}(X))=\dim\mathcal{G}_{\mathrm{mot}}(X).$$

Here $\overline{\mathbb{Q}}(\mathrm{periods}(X))$ is the field generated over $\overline{\mathbb{Q}}$ by the periods of $X$. The source notes that the full conjecture also includes connectedness of the period torsor, while this equality is the formulation used in transcendence theory.