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Filling -- a Young tableau stored column-wise

Description

A Filling is a Young tableau of partition shape, stored as a list of its columns. A filling of shape $\mu = (\mu_1 \ge \mu_2 \ge \cdots \ge \mu_r)$ with entries from an alphabet $\{0, 1, \ldots, d-1\}$ is represented by new Filling from {c_1, c_2, ..., c_{mu_1}}, where $c_j$ is the list of entries in the $j$-th column read from top to bottom. The length of $c_j$ equals $\mu'_j$, the length of the $j$-th column (equivalently, the $j$-th part of the conjugate partition $\mu'$).

Because Schur modules are built from $\wedge^{\mu'_1}(E) \otimes \cdots \otimes \wedge^{\mu'_k}(E)$, the column-wise storage makes each column directly correspond to one wedge-power tensor factor. This is the dual convention to WeylFilling, which stores rows.

i1 : T = new Filling from {{0,1}, {1,2}}

     +-+-+
o1 = |0|1|
     |1|2|
     +-+-+

o1 : Filling
i2 : toList T

o2 = {{0, 1}, {1, 2}}

o2 : List
i3 : T#0

o3 = {0, 1}

o3 : List
i4 : #T

o4 = 2

The tableau pretty-prints via its net method:

i5 : T

     +-+-+
o5 = |0|1|
     |1|2|
     +-+-+

o5 : Filling

Conjugation of a Filling produces the tableau of conjugate (transposed) shape:

i6 : conjugate T

     +-+-+
o6 = |0|1|
     |1|2|
     +-+-+

o6 : Filling
i7 : toList conjugate T

o7 = {{0, 1}, {1, 2}}

o7 : List

A filling is standard (in this package; equivalently, semistandard in the standard combinatorial sense) if its entries strictly increase down each column and weakly increase along each row. Over $\mathbb{Z}$ the standard fillings of shape $\mu$ with entries in $\{0,\ldots,d-1\}$ index a free basis of $S_\mu(R^d)$.

i8 : S = standardTableaux(3, {2,1});
i9 : #S == rank schurModule({2,1}, QQ^3)

o9 = true

See also

Methods that use an object of class Filling:

  • augmentFilling(Filling,ZZ,ZZ) -- see augmentFilling -- append an entry to a column of a Filling
  • conjugate(Filling) -- transpose of a Young tableau
  • Filling ? Filling
  • Filling _ List
  • net(Filling)
  • isStandard(Filling) -- see isStandard -- test whether a Filling is semistandard
  • normalize(Filling) -- see normalize -- sort each column of a Filling, with Koszul sign
  • straighten(Filling) -- see straighten -- straighten a filling into a linear combination of semistandard tableaux
  • straighten(Filling,Module) -- see straighten -- straighten a filling into a linear combination of semistandard tableaux

For the programmer

The object Filling is a type, with ancestor classes BasicList < Thing.


The source of this document is in /build/reproducible-path/macaulay2-1.26.05+ds/M2/Macaulay2/packages/SchurFunctors.m2:1325:0.