Claims about common cycles
Task number: 3969
Prove or refute the following statements:
Variant
Let \( G \) be a vertex 2-connected graph and \( u, v, w, z \) four of its vertices. Then there is a cycle in \( G \) containing all these vertices.
Variant
Let \( G \) be a vertex 3-connected graph and \( y, n \) two of its vertices. Then there is a cycle in \( G \) passing through the vertex \( y \) and not passing through the vertex \( n \).
Variant
Each vertex 2-connected graph \( G \) has an orientation of the edges such that for any two vertices \( u \) and \( v \) there exists in \( G \) a unidirectional cycle such that it contains \( u \) and \( v \).