Eulerian Cycle Path
1. **Problem Statement:** Determine if the given graph with vertices A, B, C, D, E, F, G, H, I, J, K and specified edges has an Eulerian cycle or an Eulerian path.
2. **Definitions:**
- An **Eulerian cycle** is a cycle that uses every edge exactly once and starts and ends at the same vertex.
- An **Eulerian path** is a path that uses every edge exactly once but does not necessarily start and end at the same vertex.
3. **Key Theorems:**
- A connected graph has an Eulerian cycle if and only if every vertex has an even degree.
- A connected graph has an Eulerian path (but not a cycle) if and only if exactly two vertices have odd degree.
4. **Calculate the degree of each vertex:**
- $\deg(A) = 3$ (connected to B, C, K)
- $\deg(B) = 1$ (connected to A)
- $\deg(C) = 2$ (connected to A, E)
- $\deg(D) = 3$ (connected to I, K, E)
- $\deg(E) = 6$ (connected to D, H, J, F, G, C)
- $\deg(F) = 1$ (connected to E)
- $\deg(G) = 1$ (connected to E)
- $\deg(H) = 2$ (connected to E, J)
- $\deg(I) = 1$ (connected to D)
- $\deg(J) = 2$ (connected to H, E)
- $\deg(K) = 2$ (connected to A, D)
5. **Count vertices with odd degree:**
- Odd degree vertices: A(3), B(1), D(3), F(1), G(1), I(1)
- Number of odd degree vertices = 6
6. **Check connectivity:**
- The graph is connected as all vertices are reachable through edges.
7. **Conclusion:**
- Since more than two vertices have odd degree, the graph does **not** have an Eulerian cycle.
- Since the number of odd degree vertices is not exactly two, the graph does **not** have an Eulerian path either.
**Final answer:** The graph has neither an Eulerian cycle nor an Eulerian path because it has 6 vertices with odd degree, which violates the necessary conditions for both.