associate $f_1$ with an appropriate conceptualization. So individual \#1 gives the same credibility to all individuals. Individuals \#2, 3 and 4 all have experienced $f_1$ and $r_1$. They evaluate individual \#1 as less credible than themselves because \#1 has not experienced $r_1$. Individual \#3 and 4 evaluate \#2 as not credible at all because she associates $r_1$ with a concept that is not probable anymore (i.e. the earth is flat while their experience shows it is round). \#2 judges herself not credible because she associates $r_1$ with an unlikely concept. Individual \#3 evaluates \#4 as less credible than herself because \#4 uses several concepts (in our model, less parsimonious conceptualizations are penalized).

Social learning
---------------

The *social learning* matrix $\Lambda \in {\mathcal{M}}_N({\mathbb R})$ represents the influence of individuals on each other. This matrix captures the effect of the structure of the population described in $\Gamma$ and the effect due to credibility $C$.

The influence of individual $j$ on $i$ depends on the structural influence $\gamma_{ij}$ of $j$ on $i$, and on the credibility $c_{ij}$ that $i$ gives to $j$. We shall assume in this work that these phenomena are *multiplicative*.

The social learning matrix $\Lambda = (\lambda_{ij})_{1 \leq i,j \leq 