Can I say a − path followed by a − path is a − path.
Because if there is a path from − followed by − I believe there should be a − path.
I don't know how to prove it.
EDIT: A − path is a path between vertex and vertex. and − path is a path between vertex and vertex
A walk is a sequence of vertices and edges of a graph i.e. if we traverse a graph, then we get a walk.
A path is a walk with no repeated vertex. This directly implies that no edges will ever be repeated
Imagine that the $vw$ path contains the vertex $u$, the concatenation of $uv$ and $vw$ is not a path, but a walk. To be a path, you have to make sure it does not contains two identical vertices.