Hub (network science)

In network science, a hub is a node with a number of links that greatly exceeds the average.

Emergence of hubs is a consequence of a scale-free property of networks.

The uprise of hubs in scale-free networks is associated with power-law distribution.

Hubs have a significantly larger number of links in comparison with other nodes in the network.

In random networks, the degree k is comparable for every node; it is therefore not possible for hubs to emerge.

In scale-free networks, nodes which emerged earlier have a higher chance of becoming a hub than latecomers.

This phenomenon is called first-mover advantage and it explains why some nodes become hubs and some do not.

However, in a real network, the time of emergence is not the only factor that influences the size of the hub.

Therefore, in real networks the growth and the size of a hub depends also on various attributes such as popularity, quality or the aging of a node.

In a scale-free network, hubs serve as bridges between the small degree nodes.

In an analysis of disease spreading or information flow, hubs are referred to as super-spreaders.

Super-spreaders may have a positive impact, such as effective information flow, but also devastating in a case of epidemic spreading such as H1N1 or AIDS.

The mathematical models such as model of H1N1 Epidemic prediction [6] may allow us to predict the spread of diseases based on human mobility networks, infectiousness, or social interactions among humans.

In a scale-free network hubs are most likely to be infected, because of the large number of connections they have.

Therefore, the selective immunization of hubs may be the cost-effective strategy in eradication of spreading disease.

Network representation of brain connectivity. Hubs are highlighted
Partial map of the Internet based on the January 15, 2005. Hubs are highlighted
Random network (a) and scale-free network (b). In the scale-free network, the larger hubs are highlighted.
The steps of the growth of the network according to the Barabasi–Albert model ( )