Let $\text{G = (V, E)}$ be a simple undirected graph, and $s$ be a particular vertex in it called the source. For $x \in \text{V},$ let $d(x)$ denote the shortest distance in $\text{G}$ from $s$ to $x$. A breadth-first search (BFS) is performed starting at $s$.
Which of the following is/are ALWAYS true?
- There are no back edges
- There are no forward edges
- For each tree edge $(u, v)$, we have $d[v]=d[u]+1$
- For each cross edge $(u, v)$, we have $d[v]=d[u]+1$