Apollonian metric

The Apollonian metric is a way of measuring distances in a specific type of geometric space called an "Apollonian disk." In this space, points are represented within circles, and distances correspond to how far apart points are based on certain geometric properties, rather than traditional straight-line distances. This metric allows for interesting properties, such as reflecting how circles shrink or expand relative to each other. It's useful in various fields, including mathematics and physics, for studying complex relationships and structures that are not easily represented in standard Euclidean geometry.