do not focus on the “dominating” physical process but, instead, integrate too many aspects that bear no relevance to the emergent properties of the system. Following up on this advice, we believe that we have successfully identified “good” proxies for the dominating processes of urban morphogenesis, namely: urban density, accessibility to road network, and accessibility to main functionalities.

#### Local scope

When the model is considered at a mesoscopic or microscopic scale, another objection could be that it seems to limit itself to an artificially “closed” urban system, neglecting important contextual phenomena such as economic exchanges. Yet, although input and output flows are greatly simplified here, they are still present in implicit form. Our simulated world is not truly closed, since newly built houses are associated with a net influx of resources. Moreover, despite the absence of a direct economic force in the growth dynamics (the $H$ index is only a post-hoc metric), the attractivity of centers constitutes a proxy for underlying activity, and a form of interdependence among urban processes. Finally, other models that have taken into account the global complex network of cities [@andersson2003urban] have reproduced well-known patterns of urban systems much like ours.

Therefore, here too, local 