通路和路徑Walks&Paths
Def: A walk is a sequence of vertices that are connected by edges.{} length k
Def: A path is a walk where all 's are different
環和迴路Cycles& closed walks
Def: A closed walk is a walk which starts and ends at exactly the same vertex.(頂點)
if k$\geq$3 and are all different,then it is called cycle
樹 Tree
Def: A definition is that a connectefd and acyclic (無環的)graph
葉節點 leaf
Def:
a leaf is a node with degree one in a tree
最小權重生成樹
Def: The MST of an edge-weighted graph G is
the ST of G with the smallest possible sum of edge weights
AlgL Grow a subgraph step by step one edge at a time
at each step:
Add minimum weight edge keeps the subgraph acyclic