301 research outputs found
Hamiltonian cycles in Cayley graphs of imprimitive complex reflection groups
Generalizing a result of Conway, Sloane, and Wilkes for real reflection
groups, we show the Cayley graph of an imprimitive complex reflection group
with respect to standard generating reflections has a Hamiltonian cycle. This
is consistent with the long-standing conjecture that for every finite group, G,
and every set of generators, S, of G the undirected Cayley graph of G with
respect to S has a Hamiltonian cycle.Comment: 15 pages, 4 figures; minor revisions according to referee comments,
to appear in Discrete Mathematic
Cayley graphs of order kp are hamiltonian for k < 48
We provide a computer-assisted proof that if G is any finite group of order
kp, where k < 48 and p is prime, then every connected Cayley graph on G is
hamiltonian (unless kp = 2). As part of the proof, it is verified that every
connected Cayley graph of order less than 48 is either hamiltonian connected or
hamiltonian laceable (or has valence less than three).Comment: 16 pages. GAP source code is available in the ancillary file
2-generated Cayley digraphs on nilpotent groups have hamiltonian paths
Suppose G is a nilpotent, finite group. We show that if {a,b} is any
2-element generating set of G, then the corresponding Cayley digraph Cay(G;a,b)
has a hamiltonian path. This implies there is a hamiltonian path in every
connected Cayley graph on G that has valence at most 4.Comment: 7 pages, no figures; corrected a few typographical error
Cayley graphs of order 27p are hamiltonian
Suppose G is a finite group, such that |G| = 27p, where p is prime. We show
that if S is any generating set of G, then there is a hamiltonian cycle in the
corresponding Cayley graph Cay(G;S).Comment: 13 pages, no figures; minor revisions, including suggestions from a
referee; this version is to appear in the International Journal of
Combinatoric
Infinitely many nonsolvable groups whose Cayley graphs are hamiltonian
This note shows there are infinitely many finite groups G, such that every
connected Cayley graph on G has a hamiltonian cycle, and G is not solvable.
Specifically, for every prime p that is congruent to 1, modulo 30, we show
there is a hamiltonian cycle in every connected Cayley graph on the direct
product of the cyclic group of order p with the alternating group A_5 on five
letters.Comment: 7 pages, plus a 22-page appendix of notes to aid the refere
Pseudo-random graphs
Random graphs have proven to be one of the most important and fruitful
concepts in modern Combinatorics and Theoretical Computer Science. Besides
being a fascinating study subject for their own sake, they serve as essential
instruments in proving an enormous number of combinatorial statements, making
their role quite hard to overestimate. Their tremendous success serves as a
natural motivation for the following very general and deep informal questions:
what are the essential properties of random graphs? How can one tell when a
given graph behaves like a random graph? How to create deterministically graphs
that look random-like? This leads us to a concept of pseudo-random graphs and
the aim of this survey is to provide a systematic treatment of this concept.Comment: 50 page
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