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Triangular fully packed loop configurations of excess 2. (English) Zbl 1351.05016

Summary: 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 \(d(w)-d(u)-d(v)=0,1\).

MSC:

05A15 Exact enumeration problems, generating functions
05A19 Combinatorial identities, bijective combinatorics

Software:

ROBBINS

References:

[1] S. Beil. Triangular fully packed loop configurations of excess 2 (extended abstract). Discr. Math. Theoret. Comput. Science, Proceedings of FPSAC 2015. · Zbl 1335.05009
[2] S. Beil, I. Fischer and P. Nadeau. Wieland drift for triangular fully packed loop configurations, Elect. J. Comb., 22(1), 2015, #P1.26. · Zbl 1307.05008
[3] L. Cantini and A. Sportiello. Proof of the Razumov-Stroganov conjecture, J. Combinatorial Theory Ser. A, 118(5):1549-1574, 2011. · Zbl 1232.05038
[4] F. Caselli, C. Krattenthaler, B. Lass and P. Nadeau. On the number of fully packed loop configurations with a fixed associated matching. Elect. J. Comb., 11(2), 2004, #R16. · Zbl 1060.05005
[5] I. Fischer, P. Nadeau. Fully Packed Loops in a triangle: matchings, paths and puzzles. J. Combinatorial Theory Ser. A, 130: 64-118, 2015. · Zbl 1303.05006
[6] G. Kuperberg. Another proof of the alternating sign matrix conjecture. Internat. Math. Res. Notices, 139-150, 1996. the electronic journal of combinatorics 23(4) (2016), #P4.1442 · Zbl 0859.05027
[7] P. Nadeau. Fully Packed Loop Configurations in a Triangle. J. Combinatorial Theory Ser. A, 120(8):2164-2188, 2013. · Zbl 1278.05062
[8] P. Nadeau.Fully Packed Loop Configurations in a Triangle and Littlewood– Richardson coefficients. J. Combinatorial Theory Ser. A, 120(8):2137-2147, 2013. · Zbl 1278.05061
[9] J. Thapper.Refined counting of fully packed loop configurations.S´eminaire Lotharingien de Combinatoire, 56:B56e:27, 2007. · Zbl 1188.05013
[10] B. Wieland. A large dihedral symmetry of the set of alternating sign matrices. Elect. J. Comb., 7, 2000, #R37. · Zbl 0956.05015
[11] D. Zeilberger. Proof of the alternating sign matrix conjecture. Elect. J. Comb., 3(2): #R13, 1996. · Zbl 0858.05023
[12] J.–B. Zuber. On the counting of Fully Packed Loop Configurations: Some new conjectures. Elect. J. Comb., 11(1): Research paper 13, 15pp, 2004. the electronic journal of combinatorics 23(4) (2016), #P4.1443 · Zbl 1054.05011
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