Classification and dimensions of simple modules of symmetric groups in characteristic p
Determine a complete classification and explicit dimension formulas for the simple (irreducible) representations of symmetric groups over a field of characteristic p > 0.
References
For example, while for symmetric groups over the complex numbers everything is well understood, over a field of characteristic $p$ a classification of the irreducible (=simple) representations or even their dimensions are generally not known.
— Rickard's Derived Morita Theory: Review and Outlook
(2509.06369 - Jasso et al., 8 Sep 2025) in Paragraph, Subsection 1.4 (Modular representation theory and splendid equivalences)