Monotonic subsequences in dimensions higher than one
The electronic journal of combinatorics, The Wilf Festschrift volume, Tome 4 (1997) no. 2
The 1935 result of Erdos and Szekeres that any sequence of at least $n^{2}+1$ real numbers contains a monotonic subsequence of at least $n+1$ terms has stimulated extensive furher research, including a paper of J.B.Kruskal that defined an extension of monotonicity for higher dimensions. This paper provides a proof of a weakened form of Kruskal's conjecture for 2 dimensional Euclidean space by showing that there exists a sequence of n points in the plane for which the longest monotonic subsequences have length $n^{2}+2$ or less.. Weaker results are also obtained for higher dimensions. The average length of the longest increasing monotonic subsequence is shown to be $\sim 2n^{1/2}$ as $n\rightarrow\infty$ for each dimension.
DOI :
10.37236/1329
Classification :
05A05, 06A07, 60C05
Mots-clés : monotonic subsequence, Kruskal's conjecture
Mots-clés : monotonic subsequence, Kruskal's conjecture
@article{10_37236_1329,
author = {A. Odlyzko and J. B. Shearer and R. Siders},
title = {Monotonic subsequences in dimensions higher than one},
journal = {The electronic journal of combinatorics},
year = {1997},
volume = {4},
number = {2},
doi = {10.37236/1329},
zbl = {0884.05001},
url = {http://geodesic.mathdoc.fr/articles/10.37236/1329/}
}
A. Odlyzko; J. B. Shearer; R. Siders. Monotonic subsequences in dimensions higher than one. The electronic journal of combinatorics, The Wilf Festschrift volume, Tome 4 (1997) no. 2. doi: 10.37236/1329
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