Article
Keywords:
line graph; path graph; cycles
Summary:
We prove that for every number $n\ge 1$, the $n$-iterated $P_3$-path graph of $G$ is isomorphic to $G$ if and only if $G$ is a collection of cycles, each of length at least 4. Hence, $G$ is isomorphic to $P_3(G)$ if and only if $G$ is a collection of cycles, each of length at least 4. Moreover, for $k\ge 4$ we reduce the problem of characterizing graphs $G$ such that $P_k(G)\cong G$ to graphs without cycles of length exceeding $k$.
References:
[1] Belan A., Jurica P.:
Diameter in path graphs. Acta Math. Univ. Comenian. New Ser. 68 (1999), 111–126.
MR 1711079
[3] Knor M., Niepel Ľ.:
Centers in path graphs. J. Comb. Inf. Syst. Sci. 24 (1999), 79–86.
MR 1871774
[5] Knor M., Niepel Ľ.: Distances in iterated path graphs. (to appear).
[6] Knor M., Niepel Ľ.:
Path, trail and walk graphs. Acta Math. Univ. Comenian. New Ser. 68 (1999), 253–256.
MR 1757793
[8] Li X., Zhao B.:
Isomorphisms of $P_4$-graphs. Australas. J. Comb. 15 (1997), 135–143.
MR 1448237