Updated information on "Positivity problems and
conjectures in algebraic combinatorics"
- A solution to
Problem 2 for convex polytopes was given by Kalle
Karu, with a strengthening
by Paul Bressler and Valery A. Lunts.
- Some progress
on Problem 4 is due to Victor Reiner and his
colloborators Naichung Conan Leung, Dennis Stanton, and Volkmar
Welker. The paper with Welker is also related to Problem 20.
- The conjecture following Problem 9 is false as stated. Pavlo
Pylyavskyy pointed out that if \lambda ≥ \lambda' then it may not
be the
case that |\Pi_\lambda| ≤ |\Pi_{\lambda'}|, the smallest example
being \lambda = (6,2,2,1,1) and \lambda' = (5,3,1,1,1,1). The
conjecture remains open if modified to state that \phi_\lambda has
full rank when \lambda ≥ \lambda', though this may very
well be false. The original conjecture remains open in the case that
would imply the Foulkes plethysm conjecture, viz., \lambda has
m parts equal to n, where n ≥
m. However, a counterexample in that case was announced by
J. Müller and Max Neunhoeffer, but details have not yet
appeared.
- A solution to the conjecture of Sundaram mentioned shortly after
Problem 9 was found by Ben Joseph in April, 2000.
- A solution
to Problem 13 (the nonnegativity of the coefficients
of the (q,t)-Kostka polynomials) has been given by Mark
Haiman.
- Problem 23 was