Intro: TreeMap Tutorial

Intro: Tree structured node-link diagrams grew too large to be useful, so I explored ways to show a tree in a space-constrained layout. I rejected strategies that left blank spaces or those that dealt with only fixed levels or fixed branching factors. Showing file size by area coding seemed appealing, but various rectangular, triangular, and circular strategies all had problems. Then while puzzling about this in the faculty lounge, I had the Aha! experience of splitting the screen into rectangles in alternating horizontal and vertical directions as you traverse down the levels. This recursive algorithm seemed attractive, but it took me a few days to convince myself that it would always work and to write a six line algorithm.