The 1-center problem is a mathematical problem, in which we are given a set of points and we must find a circle covering all these points such that the radius of the circle is minimized. It is a special case of the bounding sphere problem and the minimax facility location problem of combinatorial optimization.
The problem can be solved in linear time via the prune and search strategy. 
1. ^ Lee, R. C. T. (2005). Introduction to the design and analysis of algorithms : a strategic approach. Singapore: McGraw-Hill p.9