The paper by M. E. J. Newman explores the spread of epidemic diseases on networks, focusing on the susceptible/infective/removed (SIR) models. It demonstrates that these models can be solved exactly on various networks, including those with non-uniform and correlated transmission probabilities. The study also considers structured populations, such as the spread of sexually transmitted diseases in a population divided into men and women. The author uses percolation theory and generating function methods to derive exact solutions for outbreak sizes, epidemic thresholds, and other relevant quantities. The results are validated through numerical simulations, showing good agreement. The paper highlights the importance of network topology in disease propagation and provides insights into the conditions under which epidemics occur or can be prevented.The paper by M. E. J. Newman explores the spread of epidemic diseases on networks, focusing on the susceptible/infective/removed (SIR) models. It demonstrates that these models can be solved exactly on various networks, including those with non-uniform and correlated transmission probabilities. The study also considers structured populations, such as the spread of sexually transmitted diseases in a population divided into men and women. The author uses percolation theory and generating function methods to derive exact solutions for outbreak sizes, epidemic thresholds, and other relevant quantities. The results are validated through numerical simulations, showing good agreement. The paper highlights the importance of network topology in disease propagation and provides insights into the conditions under which epidemics occur or can be prevented.