eulerian trail造句

If there are no vertices of odd degree, all Eulerian trails are circuits.
If there are exactly two vertices of odd degree, all Eulerian trails start at one of them and end at the other.
A graph that has an Eulerian trail but not an Eulerian circuit is called "'semi-Eulerian " '.
For the existence of Eulerian trails it is necessary that zero or two vertices have an odd degree; this means the K鰊igsberg graph is " not"
It's difficult to find eulerian trail in a sentence. 用eulerian trail造句挺难的