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Identifier
Values
=>
Cc0002;cc-rep
[1]=>0 [2]=>0 [1,1]=>0 [3]=>0 [2,1]=>1 [1,1,1]=>0 [4]=>0 [3,1]=>0 [2,2]=>2 [2,1,1]=>0 [1,1,1,1]=>0 [5]=>0 [4,1]=>1 [3,2]=>0 [3,1,1]=>1 [2,2,1]=>0 [2,1,1,1]=>1 [1,1,1,1,1]=>0 [6]=>0 [5,1]=>0 [4,2]=>0 [4,1,1]=>2 [3,3]=>0 [3,2,1]=>1 [3,1,1,1]=>2 [2,2,2]=>0 [2,2,1,1]=>0 [2,1,1,1,1]=>0 [1,1,1,1,1,1]=>0 [7]=>0 [6,1]=>1 [5,2]=>1 [5,1,1]=>0 [4,3]=>1 [4,2,1]=>0 [4,1,1,1]=>3 [3,3,1]=>0 [3,2,2]=>0 [3,2,1,1]=>0 [3,1,1,1,1]=>0 [2,2,2,1]=>1 [2,2,1,1,1]=>1 [2,1,1,1,1,1]=>1 [1,1,1,1,1,1,1]=>0 [8]=>0 [7,1]=>0 [6,2]=>2 [6,1,1]=>0 [5,3]=>2 [5,2,1]=>1 [5,1,1,1]=>0 [4,4]=>2 [4,3,1]=>1 [4,2,2]=>1 [4,2,1,1]=>1 [4,1,1,1,1]=>0 [3,3,2]=>1 [3,3,1,1]=>1 [3,2,2,1]=>1 [3,2,1,1,1]=>1 [3,1,1,1,1,1]=>0 [2,2,2,2]=>2 [2,2,2,1,1]=>2 [2,2,1,1,1,1]=>2 [2,1,1,1,1,1,1]=>0 [1,1,1,1,1,1,1,1]=>0 [9]=>0 [8,1]=>1 [7,2]=>0 [7,1,1]=>1 [6,3]=>3 [6,2,1]=>0 [6,1,1,1]=>1 [5,4]=>3 [5,3,1]=>2 [5,2,2]=>2 [5,2,1,1]=>0 [5,1,1,1,1]=>1 [4,4,1]=>2 [4,3,2]=>2 [4,3,1,1]=>2 [4,2,2,1]=>2 [4,2,1,1,1]=>0 [4,1,1,1,1,1]=>1 [3,3,3]=>2 [3,3,2,1]=>2 [3,3,1,1,1]=>2 [3,2,2,2]=>2 [3,2,2,1,1]=>2 [3,2,1,1,1,1]=>0 [3,1,1,1,1,1,1]=>1 [2,2,2,2,1]=>3 [2,2,2,1,1,1]=>3 [2,2,1,1,1,1,1]=>0 [2,1,1,1,1,1,1,1]=>1 [1,1,1,1,1,1,1,1,1]=>0 [10]=>0 [9,1]=>0 [8,2]=>0 [8,1,1]=>2 [7,3]=>0 [7,2,1]=>1 [7,1,1,1]=>2 [6,4]=>4 [6,3,1]=>0 [6,2,2]=>0 [6,2,1,1]=>1 [6,1,1,1,1]=>2 [5,5]=>4 [5,4,1]=>3 [5,3,2]=>3 [5,3,1,1]=>0 [5,2,2,1]=>0 [5,2,1,1,1]=>1 [5,1,1,1,1,1]=>2 [4,4,2]=>3 [4,4,1,1]=>3 [4,3,3]=>3 [4,3,2,1]=>3 [4,3,1,1,1]=>0 [4,2,2,2]=>3 [4,2,2,1,1]=>0 [4,2,1,1,1,1]=>1 [4,1,1,1,1,1,1]=>2 [3,3,3,1]=>3 [3,3,2,2]=>3 [3,3,2,1,1]=>3 [3,3,1,1,1,1]=>0 [3,2,2,2,1]=>3 [3,2,2,1,1,1]=>0 [3,2,1,1,1,1,1]=>1 [3,1,1,1,1,1,1,1]=>2 [2,2,2,2,2]=>4 [2,2,2,2,1,1]=>4 [2,2,2,1,1,1,1]=>0 [2,2,1,1,1,1,1,1]=>0 [2,1,1,1,1,1,1,1,1]=>0 [1,1,1,1,1,1,1,1,1,1]=>0 [11]=>0 [10,1]=>1 [9,2]=>1 [9,1,1]=>0 [8,3]=>1 [8,2,1]=>0 [8,1,1,1]=>3 [7,4]=>0 [7,3,1]=>1 [7,2,2]=>0 [7,2,1,1]=>2 [7,1,1,1,1]=>3 [6,5]=>5 [6,4,1]=>0 [6,3,2]=>1 [6,3,1,1]=>1 [6,2,2,1]=>1 [6,2,1,1,1]=>2 [6,1,1,1,1,1]=>3 [5,5,1]=>4 [5,4,2]=>4 [5,4,1,1]=>0 [5,3,3]=>4 [5,3,2,1]=>1 [5,3,1,1,1]=>1 [5,2,2,2]=>0 [5,2,2,1,1]=>1 [5,2,1,1,1,1]=>2 [5,1,1,1,1,1,1]=>3 [4,4,3]=>4 [4,4,2,1]=>4 [4,4,1,1,1]=>0 [4,3,3,1]=>4 [4,3,2,2]=>4 [4,3,2,1,1]=>1 [4,3,1,1,1,1]=>1 [4,2,2,2,1]=>0 [4,2,2,1,1,1]=>1 [4,2,1,1,1,1,1]=>2 [4,1,1,1,1,1,1,1]=>3 [3,3,3,2]=>4 [3,3,3,1,1]=>4 [3,3,2,2,1]=>4 [3,3,2,1,1,1]=>1 [3,3,1,1,1,1,1]=>0 [3,2,2,2,2]=>4 [3,2,2,2,1,1]=>0 [3,2,2,1,1,1,1]=>1 [3,2,1,1,1,1,1,1]=>0 [3,1,1,1,1,1,1,1,1]=>0 [2,2,2,2,2,1]=>5 [2,2,2,2,1,1,1]=>0 [2,2,2,1,1,1,1,1]=>1 [2,2,1,1,1,1,1,1,1]=>1 [2,1,1,1,1,1,1,1,1,1]=>1 [1,1,1,1,1,1,1,1,1,1,1]=>0 [12]=>0 [11,1]=>0 [10,2]=>2 [10,1,1]=>0 [9,3]=>2 [9,2,1]=>1 [9,1,1,1]=>0 [8,4]=>0 [8,3,1]=>0 [8,2,2]=>1 [8,2,1,1]=>0 [8,1,1,1,1]=>4 [7,5]=>0 [7,4,1]=>1 [7,3,2]=>0 [7,3,1,1]=>2 [7,2,2,1]=>0 [7,2,1,1,1]=>3 [7,1,1,1,1,1]=>4 [6,6]=>6 [6,5,1]=>0 [6,4,2]=>0 [6,4,1,1]=>1 [6,3,3]=>2 [6,3,2,1]=>2 [6,3,1,1,1]=>2 [6,2,2,2]=>0 [6,2,2,1,1]=>2 [6,2,1,1,1,1]=>3 [6,1,1,1,1,1,1]=>4 [5,5,2]=>5 [5,5,1,1]=>0 [5,4,3]=>5 [5,4,2,1]=>0 [5,4,1,1,1]=>1 [5,3,3,1]=>2 [5,3,2,2]=>0 [5,3,2,1,1]=>2 [5,3,1,1,1,1]=>2 [5,2,2,2,1]=>1 [5,2,2,1,1,1]=>2 [5,2,1,1,1,1,1]=>3 [5,1,1,1,1,1,1,1]=>4 [4,4,4]=>5 [4,4,3,1]=>5 [4,4,2,2]=>5 [4,4,2,1,1]=>0 [4,4,1,1,1,1]=>0 [4,3,3,2]=>5 [4,3,3,1,1]=>2 [4,3,2,2,1]=>0 [4,3,2,1,1,1]=>2 [4,3,1,1,1,1,1]=>0 [4,2,2,2,2]=>0 [4,2,2,2,1,1]=>1 [4,2,2,1,1,1,1]=>2 [4,2,1,1,1,1,1,1]=>0 [4,1,1,1,1,1,1,1,1]=>0 [3,3,3,3]=>5 [3,3,3,2,1]=>5 [3,3,3,1,1,1]=>2 [3,3,2,2,2]=>5 [3,3,2,2,1,1]=>0 [3,3,2,1,1,1,1]=>0 [3,3,1,1,1,1,1,1]=>1 [3,2,2,2,2,1]=>0 [3,2,2,2,1,1,1]=>1 [3,2,2,1,1,1,1,1]=>0 [3,2,1,1,1,1,1,1,1]=>1 [3,1,1,1,1,1,1,1,1,1]=>0 [2,2,2,2,2,2]=>6 [2,2,2,2,2,1,1]=>0 [2,2,2,2,1,1,1,1]=>0 [2,2,2,1,1,1,1,1,1]=>2 [2,2,1,1,1,1,1,1,1,1]=>2 [2,1,1,1,1,1,1,1,1,1,1]=>0 [1,1,1,1,1,1,1,1,1,1,1,1]=>0 [5,4,3,1]=>0 [5,4,2,2]=>1 [5,4,2,1,1]=>1 [5,3,3,2]=>0 [5,3,3,1,1]=>3 [5,3,2,2,1]=>1 [4,4,3,2]=>6 [4,4,3,1,1]=>0 [4,4,2,2,1]=>1 [4,3,3,2,1]=>0 [5,4,3,2]=>1 [5,4,3,1,1]=>1 [5,4,2,2,1]=>2 [5,3,3,2,1]=>1 [4,4,3,2,1]=>1 [5,4,3,2,1]=>2
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Description
The smallest integer d such that the restriction of the representation corresponding to a partition of n to the symmetric group on n-d letters has a constituent of odd degree.
For example, restricting $S_{(6,3)}$ to $\mathfrak S_8$ yields $$S_{(5,3)}\oplus S_{(6,2)}$$ of degrees (number of standard Young tableaux) 28 and 20, none of which are odd. Restricting to $\mathfrak S_7$ yields $$S_{(4,3)}\oplus 2S_{(5,2)}\oplus S_{(6,1)}$$ of degrees 14, 14 and 6. However, restricting to $\mathfrak S_6$ yields
$$S_{(3,3)}\oplus 3S_{(4,2)}\oplus 3S_{(5,1)}\oplus S_6$$ of degrees 5,9,5 and 1. Therefore, the statistic on the partition $(6,3)$ gives 3.
This is related to $2$-saturations of Welter's game, see [1, Corollary 1.2].
References
[1] Irie, Y. p-Saturations of Welter's Game and the Irreducible Representations of Symmetric Groups arXiv:1604.07214
Code
def branching_symmetric_group(la, p):
    """
    Return a dictionary from partitions to multiplicities.
    """
    la = Partition(la)
    l = {la: 1}
    for i in range(la.size()-p):
        l_new = dict()
        for mu in l:
            for r, _ in mu.removable_cells():
                nu = mu.remove_cell(r)
                l_new[nu] = l_new.get(nu, 0) + l[mu]
        l = l_new
    return l

def statistic(la):
    """Return the largest number such that the restriction of the
    irreducible representation corresponding to la has a component
    relative prime to 2.
    """
    la = Partition(la)    
    for m in range(la.size(), 0, -1):
        if any(gcd(StandardTableaux(mu).cardinality(), 2) == 1
               for mu in branching_symmetric_group(la, m)):
            return la.size()-m
Created
Apr 05, 2017 at 11:28 by Martin Rubey
Updated
Sep 14, 2018 at 18:56 by Martin Rubey