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Immanant


The immanant I_lambda(A) of an n×n matrix A=(a_(ij)), indexed by a partition lambda of n, is the weighted sum

 I_lambda(A)=sum_(sigma in S_n)chi^lambda(sigma)product_(i=1)^na_(i,sigma(i)),

where chi^lambda is the irreducible group character of the symmetric group S_n indexed by lambda (Littlewood and Richardson 1934a). The partitions (n) and (1^n) give the permanent and determinant, respectively.

For 1<=k<=n and lambda_k=(k,1^(n-k)), the dimension of the corresponding irreducible representation is chi^(lambda_k)(e)=n-1k-1, where e is the identity permutation. Skandera (2026, p. 16) proved that for n>=2 every n×n totally nonnegative matrix satisfies

 perA=(I_(lambda_n)(A))/(n-1n-1)>=(I_(lambda_(n-1))(A))/(n-1n-2)>=...>=(I_(lambda_1)(A))/(n-10)=detA.

The hypothesis requires all minors to be nonnegative, rather than only the entries. The inequalities above concern the specified partitions.


See also

Determinant, Permanent, Totally Nonnegative Matrix

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References

Littlewood, D. E. and Richardson, A. R. "Group Characters and Algebra." Philos. Trans. Roy. Soc. London A 233, 99-141, 1934a.Littlewood, D. E. and Richardson, A. R. "Immanants of Some Special Matrices." Quart. J. Math. (Oxford) 5, 269-282, 1934b.Skandera, M. "Hook Immanantal Inequalities for Totally Nonnegative Matrices." Elec. J. Combin. 33, P4.23, 2026. https://doi.org/10.37236/14684.Wybourne, B. G. "Immanants of Matrices." §2.19 in Symmetry Principles and Atomic Spectroscopy. New York: Wiley, pp. 12-13, 1970.

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Immanant

Cite this as:

Weisstein, Eric W. "Immanant." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Immanant.html

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