Paths and Circuits of a Graph
Path = sequence of arcs (x1? x2 , x2? x3 , x3? x4 , … xk-1? xk)
Also can write [x1,x2 ,x3,…, xk]
Simple if does not use the same arc twice, else composite
Elementary if does not use same vertex twice
Can be finite or infinite
Circuit = path [x1,x2 ,x3,…, xk] where initial vertex x1= terminal vertex xk
Elementary circuit if all vertices distinct apart from x1= xk
Length of path (x1? x2 , … xk-1? xk) is K-1
Loop is circuit length=1, I.e. (x1? x1)