$\mathcal{C}$, $\mathcal{P}$:	Total number of countries and products
$\mathbf{M}$:	Binary matrix with element $M_{cp}=1$ if country c is a competitive country in exporting product p; $M_{cp}=0$ otherwise; export competitiveness is estimated by means of export volumes
$F_c$, $Q_p$:	Fitness of country c and quality (complexity) of product p at the fixed point
$P_p$:	Inverse of the quality of product p; it is a sort of product “simplicity” ($P_p={\left(Q_p\right)}^{-1}$)
$\delta$:	Inhomogeneous parameter; this parameter is crucial in achieving a stable algorithm to evaluate the metrics; it will be eventually let go to 0 to get a parameter free metric
${\tilde{F}}_c,{\tilde{P}}_p$:	Rescaled versions of the corresponding un-tilded quantities: ${\tilde{F}}_c=F_c\delta$, ${\tilde{P}}_p=P_p/\delta$; these quantities do not depend on $\delta$ as soon as $\delta \to 0$ and are better suited to represent fitness and complexity rather than the un-tilded ones
${\tilde{Q}}_p$:	Similar to the complexity $Q_p$ above, but for the new metrics calculated with the inhomogeneous algorithm: ${\tilde{Q}}_p={({\tilde{P}}_p-1)}^{-1}$
$\mathbf{K}$:	Coproduction matrix with element $K_{c{c}^{\prime }}$ equal to the number of the same products exported by countries c and $c^{\prime }$; $\mathbf{K}=\mathbf{M}{\mathbf{M}}^T$
$D_c$:	Diversification of country c, i.e., the number of products the country c is competitive in exporting
$I_c$:	Inefficiency of country c defined as $I_c=D_c-{\tilde{F}}_c$; it represents the fitness penalty resulting from exporting goods that are also exported by other countries
$N_c$:	Net-efficiency of country c; it is a de-trended version of the inefficiency; in the dataset considered $N_c\approx D_c^{0.75}-I_c$; it represents how effectively a country diversifies its exported goods by focusing on products not exported by others, which are usually among the most complex ones