Combinatorial interpretation of Schubert structure constants
Find a combinatorial interpretation of Schubert structure constants as counts of explicitly describable combinatorial objects, such as paths in Bruhat order, Mondrian tableaux, labeled diagrams, permutation arrays, or n-dimensional chess games.
References
This is why the problem above is still considered a major open problem in this field.
— Introduction to the Cohomology of the Flag Variety
(2506.21064 - Billey et al., 26 Jun 2025) in Problem prob:structure.constants, subsection “Solving Schubert Problems in 2000 (Reprise)”