有向图2k·_5及2k·_7的优美性

On the Gracefalness of the Digraph 2k·C 5 and 2k·C 7

杜之亭（１９９４）中提出的猜想：在ｎＣ２ｐ＋１（ｐ∈Ｎ），在ｎ≡０（ｍｏｄ２）时是优美图。证明了，当ｐ＝２。

Abstract Reference adranced to conjecture: n·C 2p+1 (p∈N) is graceful graph when n≡0( mod 2) . In this paper proved its validity duo to p=2,3 .