Greg writes:

“I’m currently a Ph.D. student studying maths in Australia (submitting next week). The the tattoo on the top, I got about three years ago in Berkeley, CA. The other tattoo I got about a year later in Sydney, Australia. Both these tattoos are closely related to the research I’ve done for my Ph.D., which is in the area of elliptic partial differential equations. The top equation is called the Monge-Ampere equation and is the archetype of the equations I currently study. The bottom equation is called the ‘Infinity Laplacian’ and was chosen because it is correlated to variational theories which I find to be beautiful. Loosely speaking these equations are correlated to how surfaces (in arbitrary dimension) bend and curve. I figured since I did half my Ph.D. in the US and half in Australia, I would get at least one tattoo in each of those countries. The tattoos are meant to represent a memory of the time I spent in my studies.”