1. The problem statement, all variables and given/known data As the title says, which branch of mathematics predominates in the equation below? 2. Relevant equations Source: http://en.wikibooks.org/wiki/Macroeconomics/Optimal_Growth 3. The attempt at a solution I'm not very familiar with the max operator, and don't really know where it comes from. However, I'm familiar with the summation notation used here.