We say a digraph G is hyperhamiltonian if there is a spanning closed walk in G which passes through one vertex exactly twice and all others exactly once. We show the Cartesian product Z, x Z, of two directed cycles is hyperhamiltonian if and only if there are positive integers rn and n with ma + nb
Full friendly index sets of Cartesian products of two cycles
โ Scribed by Wai Chee Shiu; Man Ho Ling
- Publisher
- Institute of Mathematics, Chinese Academy of Sciences and Chinese Mathematical Society
- Year
- 2010
- Tongue
- English
- Weight
- 238 KB
- Volume
- 26
- Category
- Article
- ISSN
- 1439-7617
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## Abstract We show that the Cartesian product of two directed cycles __Z__~__a__~ X __Z__~__b__~ has __r__ disjointly embedded circuits __C__~1~, __C__~2~, โ, __C__~r~ with specified knot classes knot__(C~i~) = (m~i~, n~i~)__, for __i__ = 1, 2, โ, __r__, if and only if there exist relatively prime
We find necessary and sufficient conditions for the existence of a closed walk that traverses r vertices twice and the rest once in the Cayley digraph of 2, @ 2,. This is a generalization of the results known for r = 0 or 1. In 1978, Trotter and Erdos [3] gave a necessary and sufficient condition f
We show that the Cartesian product Z, x Z, of two directed cycles is hypo-Hamiltonian (Hamiltonian) if and only if there is a pair of relatively prime positive integers m and n with ma + nb = ab -1 (ma + nb = ab). The result for hypo-Hamiltonian is new; that for Hamiltonian is known. These are speci