A Littlewood-Richardson coefficient is the nonnegative
integer coefficient in the expansion of a product
of Schur polynomials:
|
(1)
|
The partitions satisfy when the coefficient
is nonzero. The identity is understood in sufficiently many variables, or in the
ring of symmetric functions.
Equivalently, for
and
,
is the multiplicity of the Specht module
in the representation of
induced from
for
(Macdonald 1995). Thus these coefficients
concern induction between different symmetric groups,
whereas a Kronecker coefficient concerns
a vector space tensor product of representations
of the same symmetric group. For example,
.
The Littlewood-Richardson rule counts the semistandard skew tableaux of shape and content
whose row-reading word is a lattice word. Rows are read from
right to left, beginning with the top row. Lattice means that in every initial segment
the number of occurrences of
is at least the number of occurrences of
, for every positive
integer
(Macdonald 1995).
Write for the dimension of the
Specht module indexed by a partition
of size
, and define its dimension deficit by
|
(2)
|
For
and
, put
.
Slonim (2026) reports that, for every fixed
,
there are positive constants
and
such that
|
(3)
|
whenever and
.
The requirement that the coefficient be positive
is essential to this finite-deficit statement.
Large dimensions alone do not force positivity. For every fixed , Slonim (2026) reports an
such that, for every sufficiently large even
and every pair of partitions
and
of
with
, there is
a partition
of
with
and
. This assertion concerns vanishing
coefficients, not an arbitrarily small positive coefficient.
For , the same work reports
. When
and the diagram of
is contained in that of
, equality holds iff the
skew shape
has at most one box in each row and each column. For
a shape of that kind, equality holds for every partition
of its size.
Let
and let
be the largest
over partitions
of sizes
,
,
and
. Slonim (2026) reports the exact stabilization threshold
|
(4)
|
for
and
. The exceptions are
,
,
and
, for which
for every
,
using the empty partition at
. The equality construction uses a skew shape consisting
of
boxes with at most one in each row and each column. For example, at
with
,
take
and
.
Slonim attributes the mathematical statements and proofs to ChatGPT 6 Pro and explicitly states that the technical proofs have not been independently verified.