A (n,5) - cage is a minimal graph of regular degree n and girth 5. Let f(n,5) denote the number of vertices in a (n,5) - cage. The best known example of an (n,5) - cage is the Petersen graph, the (3,5) - cage. The (4,5) - cage is the Robertson graph, the (7,5) - cage is the Hoffman- Singleton graph, the (6,5) - cage was found by O'Keefe and Wong and there are three known (5,5) - cages. No other
... [Show full abstract] (n,5) - cages are known for n ≥ 8. In this paper, we will use a graph structure called remote edges and a set of mutually orthogonal Latin squares to give an upper bound of f(n,5) for n = 2k + 1.