Relative combinatorial invariance conjecture for relative R-polynomials

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Let (W,S)(W,S) be a finite Coxeter system. For a subset J⊆SJ\subseteq S, write WJW_J for the corresponding standard parabolic subgroup. For pairs in finite Coxeter systems, let G[σi,ωi]G[\sigma_i,\omega_i] be their directed Bruhat intervals and let Rσi,ωi,JR_{\sigma_i,\omega_i,J} denote the JJ-relative RR-polynomial. Relative combinatorial invariance conjecture. For every finite Coxeter system (W,S)(W,S), there is an assigned subset J(W)⊊S\mathbb{J}(W)\subsetneq S such that, whenever two Bruhat intervals are isomorphic by ϕ\phi and every edge σ1≤z<tz≤ω1\sigma_1\leq z<tz\leq\omega_1 satisfies

t∈(W1)J(W1)⟺ϕ(tz)ϕ(z)−1∈(W2)J(W2),t\in (W_1)_{\mathbb{J}(W_1)}\quad\Longleftrightarrow\quad \phi(tz)\phi(z)^{-1}\in (W_2)_{\mathbb{J}(W_2)},

one has

Rσ1,ω1,J(W1)=Rσ2,ω2,J(W2).R_{\sigma_1,\omega_1,\mathbb{J}(W_1)}=R_{\sigma_2,\omega_2,\mathbb{J}(W_2)}.

This is proposed as a relative analogue of combinatorial invariance, formulated through JJ-relative RR-polynomials. Its status is not specified in the supplied text.

References

Primary source

Maxim Gurevich and Chuijia Wang, “Parabolic recursions for Kazhdan-Lusztig polynomials and the hypercube decomposition”, arXiv:2303.09251 (2023).

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