External Professor Raissa D’Souza has won the Network Science Society’s inaugural Euler award for her influential work in "the discovery and study of explosive percolation in networks and the insights it provided to explosive synchronization and network optimization.”

Explosive percolation describes a rapid phase transition in a network where nodes abruptly shift from being relatively isolated to massively connected. It offers insights for understanding and controlling real-world phenomena that arise in transportation networks, disease spread, the growth of the Internet, power grid failures, and financial crashes.

D’Souza and her colleagues Dmitri Achlioptas and Joel Spencer first introduced their model of explosive percolation in 2009 in a landmark paper in the journal Science. The model demonstrated a radically new way for random networks to grow connections when just a small bit of direction is introduced.

The conventional understanding of random networks holds that connections build gradually, in a way that a 2015 Quanta article likened to "to the way water moves through freshly ground coffee beans, slowly saturating all the granules to become coffee in the container below."

In contrast to the slow-brewing “coffee" model of percolation, the 2009 paper presented a form of percolation that was discontinuous and near-instantaneous. D’Souza and colleagues’ algorithm generated explosive percolation by introducing a selection rule, with criteria that dictate which of two possible new connections will form. When the algorithm chooses to connect smaller groups instead of larger ones, the overall level of connectivity stays low until the network reaches a critical point, where connections suddenly explode. Such a phenomenon could be catastrophic in a scenario of disease control, where trying to minimize connections between susceptible and infected individuals could have the unintended consequence of precipitating sudden, widespread connectivity and epidemic outbreak.

"Raissa’s work with Achlioptas and Spencer shows that many processes in networks—communities, epidemics, and synchronization—can occur even more suddenly than we thought before, jumping directly from small isolated groups or outbreaks to a huge fraction of the population,” said Professor Cris Moore. “Raissa is also a leading light in the study of 'networks of networks,' revealing surprising interactions between networks of different types like power, transportation, and communication.”

Since the 2009 Science paper, the study of explosive percolation has taken off, in network science and in other fields including explosive synchronization. D’Souza has recently published a 100-page review article of state-of-the-art techniques in explosive phenomena on complex networks in the journal Advances in Physics.

D’Souza accepted her award at the 2019 NetSci Conference in Burlington, VT.

She is based at the University of California, Davis, where she works across departments for Computer Science, Mechanical and Aerospace Engineering, and Complexity Science.

Read the UC Davis announcement.

Read more about the Euler award on the Network Science Society website.