ArticlesFrancois Bergeron, $(\operatorname {GL}_k \times \ \mathbb {S}_n)$-modules of multivariate diagonal harmonicsFrancesco Brenti, Some open problems on Coxeter groups and unimodalityR. Kenyon, Some combinatorial problems arising in the dimer modelPer Alexandersson and Valentin Feray, A positivity conjecture on the structure constants of shifted Jack functionsGreta Panova, Complexity and asymptotics of structure constantsJonathan Novak and Brendon Rhoades, Increasing subsequences and Kronecker coefficientsNathan Williams, Combinatorics and braid varietiesIsabella Novik and Hailun Zheng, Neighborly spheres and transversal numbersHugh Thomas, Realizing simplicial complexes as the boundary of the totally non-negative part of a varietySam Hopkins, Order polynomial product formulas and poset dynamicsThomas Lam, An invitation to positive geometriesSatoshi Murai, An upper bound problem for triangulations of manifoldsIgor Pak, What is a combinatorial interpretation?James Propp, Trimer covers in the triangular grid: Twenty mostly open problemsLaura Colmenarejo, Rosa Orellana, Franco Saliola, Anne Schilling and Mike Zabrocki, The mystery of plethysm coefficientsTri Lai, Problems in the enumeration of tilingsZhao Gao, Claudiu Raicu and Keller VandeBogert, Some questions arising from the study of cohomology on flag varietiesAlexander Yong, Castelnuovo-Mumford regularity and Schubert geometryRalf Schiffler, Perfect matching problems in cluster algebras and number theory