Complete Sets of Metamorphoses: Paired Stars into 4-Cycles

Elizabeth J. Billington1, Abdollah Khodkar2, C.C. Lindner3
1School of Mathematics and Physics The University of Queensland Queensland 4072 Australia
2Department of Mathematics University of West Georgia Carrollton, GA 30118 U.S.A,
3Department of Mathematics and Statistics Auburn University Auburn, AL 36849 U.S.A.

Abstract

If an edge-disjoint decomposition of a complete graph of order \( n \) into copies of a \( 3 \)-star (i.e., the graph \( K_{1,3} \) on \( 4 \) vertices) is taken, and if these \( 3 \)-stars can be paired up in three distinct ways to form a graph on \( 6 \) vertices consisting of a \( 4 \)-cycle with two opposite pendant edges, such that:
(1) in each of the three pairings, there exists a metamorphosis into a \( 4 \)-cycle system; (2) taking precisely those \( 4 \)-cycles formed from the two pendant edges from each pair of \( 3 \)-stars, in each of the three metamorphoses, we again have a \( 4 \)-cycle system of the complete graph, then this is called a complete set of metamorphoses from paired \( 3 \)-stars into \( 4 \)-cycles.

We show that such a complete set of metamorphoses from paired \( 3 \)-stars into \( 4 \)-cycles exists if and only if the order of the complete graph is \( 1 \) or \( 9 \pmod{24} \), and greater than \( 9 \).