What is the definition of circuit in math?
Circuit is a term often used in graph theory. Here is how it is
defined: A simple circuit on n vertices, Cn is a connected graph
with n vertices x1, x2,..., xn, each of which has degree 2, with xi
adjacent to xi+1 for i=1,2,...,n-1 and xn adjacent to x1. Simple
means no loops or multiple edges.