Lattice points and simultaneous core partitions
The electronic journal of combinatorics, Tome 25 (2018) no. 3
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Zbl arXiv
We apply lattice point techniques to the study of simultaneous core partitions. Our central observation is that for $a$ and $b$ relatively prime, the abacus construction identifies the set of simultaneous $(a,b)$-core partitions with lattice points in a rational simplex. We apply this result in two main ways: using Ehrhart theory, we reprove Anderson's theorem that there are $(a+b-1)!/a!b!$ simultaneous $(a,b)$-cores; and using Euler-Maclaurin theory we prove Armstrong's conjecture that the average size of an $(a,b)$-core is $(a+b+1)(a-1)(b-1)/24$. Our methods also give new derivations of analogous formulas for the number and average size of self-conjugate $(a,b)$-cores.
DOI :
10.37236/5734
Classification :
11P81, 52B20, 05A17
Mots-clés : partitions, rational Catalan combinatorics, Ehrhart theory
Mots-clés : partitions, rational Catalan combinatorics, Ehrhart theory
Affiliations des auteurs :
Paul Johnson  1
Paul Johnson. Lattice points and simultaneous core partitions. The electronic journal of combinatorics, Tome 25 (2018) no. 3. doi: 10.37236/5734
@article{10_37236_5734,
author = {Paul Johnson},
title = {Lattice points and simultaneous core partitions},
journal = {The electronic journal of combinatorics},
year = {2018},
volume = {25},
number = {3},
doi = {10.37236/5734},
zbl = {1439.11267},
url = {http://geodesic.mathdoc.fr/articles/10.37236/5734/}
}
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