Grassmann-necklace containment conjecture for covers of positroids

Let PnP_n be the poset of positroids on [n][n], ordered by the quotient relation. For τ1,τ2otinPn\tau_1,\tau_2 otin P_n? Let τ1,τ2otinPn\tau_1,\tau_2 otin P_n be such that τ1otτ2\tau_1 ot\triangleleft\tau_2. Let Ii=(I1i,,Ini)I_i=(I_1^i,\cdots,I_n^i) be the Grassmann necklace of τi\tau_i, for i=1,2i=1,2, respectively. Grassmann-necklace containment conjecture. If

τ1τ2,\tau_1\lessdot\tau_2,

then

Ij1Ij2I_j^1\subseteq I_j^2

for each j[n]j\in[n]. This has been checked for flags of positroids obtained from a single matrix representation; containment of Grassmann necklaces alone does not guarantee the quotient property.

Sources & referencesView supporting material

Primary source

Carolina Benedetti, Anastasia Chavez and Daniel Tamayo, “Quotients of uniform positroids”, arXiv:1912.06873 (2019).

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