Barrett, Eubank, and Smith write in the current SciAm on the subject of EpiSims

To understand what a social network is and how it can be used for epidemiology, imagine the daily activities and contacts of a single hypothetical adult, Ann. She has short brushes with family members during breakfast ad then with other commuters or carpoolers on her way to work . . . We can visually represent Ann’s contacts as a network with Ann in the center and a line connecting Ann to each of them. All Ann’s contacts engage in various activities and meet other people as well. We can represent these “contacts of contacts” by drawing lines from each–for example, Ann’s colleague named Bob–to all his contacts. Unless they are also contacts of Ann, Bob’s contacts are two “hops” away from Ann. The number of hops on the shortest path between people is sometimes called the graph distance or degree of separation between those people.

Here’s A: what does A do when confronted with A.1 or A.2? Hense, hypertext, simulation, and the choices in writing. Mind.