GRAPHS WITHOUT REPEATED CYCLE LENGTHS

In 1975, P. Erdös proposed the problem of determining the maximum number f(n) of edges in a graph of n vertices in which any two cycles are of different lengths. In this paper, it is proved that f(n) ≥ n + 36t for t = 1260r + 169 (r ≥ 1) and n ≥ 540t2 + 175811 2 t + 798