Figure 4.

(color online) Complexity of models for $n=4$ as a function of the number $\left|\mathcal{M}\right|$ of operators: Each triangle represents a class of complexity, which contains one or more models (see Section SM-6 of the Supplementary Material). For each class, the value of $c_{\mathcal{M}}$ was obtained from a representative of the class; some of them are shown here with their corresponding diagram (same notation as in Figure 1). The triangle colors indicate the values of $n_{\mathcal{M}}$: Violet for $n_{\mathcal{M}}=4$, green for 3, yellow for 2, pink for 1, and red for 0 (model with no operator). Models on the black line have only independent operators ($\left|\mathcal{M}\right|=n_{\mathcal{M}}$) and complexity, $c_{\mathcal{M}}=\left|\mathcal{M}\right|log\pi$; models on the dashed curve are complete models, the complexities of which are given in (9). Complexity classes with the same values of $\left|\mathcal{M}\right|$ and $n_{\mathcal{M}}$ have the same value of $\lambda =\left|\mathcal{M}\right|-n_{\mathcal{M}}$, i.e., the same number of loops, $\left|\mathcal{L}\right|$, but a different loop structure.