ABSTRACT
Recursion is an everyday phenomenon that is natural to the human mind. Sometimes recursive computer programs can be challenging to reason about; however, recursion itself is readily understandable. For example, every person has parents, who have parents, who have parents, etc. That is an example of recursion. For another example, take two mirrors and make them face each other. A characteristic pattern will appear with images within images within images, etc. We also see recursion in cell-growth, and this manifests in the shapes of living things. For example, a tree’s trunk is divided into main branches. Each branch in turn is further divided into smaller branches. Smaller branches are divided into twigs, and eventually we have leaves. This is the third example of recursion. In this case the recursive branching of the trunk into twigs is bounded by the leaves. Recursion is everywhere around us, and is also part of us. It is part of language, the way we think, and how our bodies grow. Recursion is one of nature’s ways for solving complex problems.
