The Ordovician lattice structure conjecture

From papers

An Ordovician lattice is obtained from a Cambrian lattice by a finite sequence of mutations. For an Ordovician lattice LL, let a,ba,b be atoms, let μi(L)\mu_i(L) denote mutation at an atom ii, and let B\overrightarrow{B} be the quiver corresponding to LL.

Ordovician lattice structure conjecture. The following hold:

  1. Every Ordovician order is a lattice. In particular, every Cambrian lattice is mutable. Moreover, u(x)u(x) is obtained from xx by a rotation sending each vertex to the next vertex clockwise.
  2. If a,ba,b are atoms of LL, then [0,ab][0,a\vee b] is a (2,m)(2,m)-polygon for some m2m\geq 2. Moreover, LL is polygonal: [x,yz][x,y\vee z] is a polygon for any xy,zx\prec y,z, and [xy,z][x\wedge y,z] is a polygon for any x,yzx,y\prec z.
  3. If LL corresponds to B\overrightarrow{B} and iLi\in L is an atom, then μi(L)\mu_i(L) corresponds to μi(B)\mu_i(\overrightarrow{B}).

The supplied text gives no resolution. The statement packages structural, polygonality, and mutation-compatibility properties of Ordovician lattices.

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Sources & referencesView supporting material

Primary source

Kan Nagano, “Flip of lattices”, arXiv:2605.09601 (2026).

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