Triangular fully packed loop configurations of excess 2
The electronic journal of combinatorics, Tome 23 (2016) no. 4
Triangular fully packed loop configurations (TFPLs) came up in the study of fully packed loop configurations on a square (FPLs) corresponding to link patterns with a large number of nested arches. To a TFPL is assigned a triple $(u,v;w)$ of $01$-words encoding its boundary conditions which must necessarily satisfy that $d(u)+d(v)\leq d(w)$, where $d(u)$ denotes the number of inversions in $u$. Wieland gyration, on the other hand, was invented to show the rotational invariance of the numbers of FPLs having given link patterns. Later, Wieland drift — a map on TFPLs that is based on Wieland gyration — was defined. The main contribution of this article will be a linear expression for the number of TFPLs with boundary $(u,v;w)$ where $d(w)-d(u)-d(v)=2$ in terms of numbers of stable TFPLs, that is, TFPLs invariant under Wieland drift. This linear expression generalises already existing enumeration results for TFPLs with boundary $(u,v;w)$ where $d(w)-d(u)-d(v)=0,1$.
DOI :
10.37236/5536
Classification :
05A15, 05A19
Mots-clés : triangular fully packed loop configurations, Wieland gyration
Mots-clés : triangular fully packed loop configurations, Wieland gyration
Affiliations des auteurs :
Sabine Beil  1
@article{10_37236_5536,
author = {Sabine Beil},
title = {Triangular fully packed loop configurations of excess 2},
journal = {The electronic journal of combinatorics},
year = {2016},
volume = {23},
number = {4},
doi = {10.37236/5536},
zbl = {1351.05016},
url = {http://geodesic.mathdoc.fr/articles/10.37236/5536/}
}
Sabine Beil. Triangular fully packed loop configurations of excess 2. The electronic journal of combinatorics, Tome 23 (2016) no. 4. doi: 10.37236/5536
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