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A122026 Least number m such that every tournament with at least m nodes contains the acyclic n-node tournament. 1
0, 1, 2, 4, 8, 14, 28 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
A Ramsey-like number but defined for tournaments (i.e., directed graphs in which each node-pair is joined by exactly one arc) rather than undirected graphs.
It is not hard to show that a(n) always exists and a(n) is nondecreasing.
The lower bounds a(4)>=8 and a(5)>=14 and a(6)>=28 arise from the cyclic tournaments with offsets 1,2,4 mod 7; the same is true of offsets 1,3,9,2,6,5 mod 13 and the "QRgraph" in GF(3^3) with 27 vertices.
The following lower bounds a(n)>=P+1 arise from QRgraph(P) where P is prime and P=3 (mod 4): a(8)>=48, a(9)>=84, a(10)>=108, a(12)>=200, a(13)>=272.
This is almost certainly different from the other sequences currently in the OEIS which begin 1,2,4,8,14,28.
REFERENCES
K. B. Reid, Tournaments, in Handbook of Graph Theory; see p. 167.
LINKS
Yahoo Groups, Range Voting
Range Voting Yahoo Group, Introduction. [Cached copy]
RangeVoting.org, Group Website.
CROSSREFS
Sequence in context: A164147 A321402 A210669 * A196721 A118034 A096590
KEYWORD
nonn
AUTHOR
Warren D. Smith, Sep 11 2006
STATUS
approved

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Last modified July 14 09:01 EDT 2024. Contains 374318 sequences. (Running on oeis4.)