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 \( v \).

Difficulty level: Easy task (using definitions and simple reasoning)
Reasoning task
Proving or derivation task
Cs translation
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