Let G $=($V$,$E$)$ be a directed graph and let s be a vertex in V from which all

other vertices are reachable. Assume a BFS is started at s$.$ It assigns to each vertex v a

number $\backslash$delta $($v$)$ which indicates the level of the constructed BFS tree that contains v$.$ In other

words $\backslash$delta $($v$)$ is the number of edges on a shortest path from s to v$.$

If $[$u$,$ v$$ is an edge in E$,$ what is the relationship between $\backslash$delta $($u$)$ and $\backslash$delta $($v$)?$