Keys, frank words and matrix realizations of pairs of tableaux
 
 
Description:  In this talk, we consider the problem of the existence of a matrix realization, over a local principal ideal domain, for a pair $(T,K(\sigma))$, where $T$ is a skew tableau over the alphabet $\{1,\ldots,t\}$ and $K(\sigma)$ is the key associated with the permutation $\sigma\in S_t$ with the same evaluation as $T$. Using a variant of the dual Robinson-Schensted-Knuth correspondence, we determine a necessary condition for the existence of a matrix realization for $(T,K(\sigma))$, generalizing the existing results for the permutations identity, reverse and transpositions of two consecutive integers. This condition is also sufficient when the word of $T$ is a shuffle of all columns of $K(\sigma)$. The shuffle of all columns of $K(\sigma)$ is always a subset of the plactic class of $K(\sigma)$. The problem is, therefore, completely solved for the permutations whose plactic classes of associated keys are characterized by the shuffle of their columns. This family of permutations is identified. We also solve the problem for the keys associated with the symmetric group $S_4$, where there are keys whose plactic classes cannot be described by the shuffle of their columns. In particular, the analysis of the case $\sigma\in S_3$ allows us to generalize the action of the symmetric group on frank words and words congruent with keys described by Lascoux and Sch\"utzenberger.
Area(s):
Date:  2006-06-20
Start Time:   14:45
Speaker:  Ricardo Mamede (CMUC / Matemática FCTUC)
Place:  5.5
Research Groups: -Algebra and Combinatorics
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