Marietti's parabolic Combinatorial Invariance Conjecture

Let (W1,S1)(W_1,S_1) and (W2,S2)(W_2,S_2) be Coxeter systems, with J1S1J_1\subseteq S_1 and J2S2J_2\subseteq S_2. Let u,vW1J1u,v\in W_1^{J_1}, w,zW2J2w,z\in W_2^{J_2}, and let f:[u,v][w,z]f:[u,v]\to[w,z] be a poset isomorphism satisfying

f([u,v]J1)=[w,z]J2.f([u,v]^{J_1})=[w,z]^{J_2}.

Parabolic Combinatorial Invariance Conjecture. Then

Pu,vJ1,q(q)=Pw,zJ2,q(q).P_{u,v}^{J_1,q}(q)=P_{w,z}^{J_2,q}(q).

The naive parabolic version is false in general, whereas this deeper formulation is known when u=w=eu=w=e and remains open in general.

Sources & referencesView supporting material

Primary source

Francesco Brenti, “Some open problems on Coxeter groups and unimodality”, arXiv:2410.09897 (2024).

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