Multiplicability conjecture for finitary upho lattices

Let PP be an upho lattice, meaning an upho poset whose order is a lattice, and suppose that PP is finitary. It is multiplicable if it admits a left-cancellative, invertible-free monoid structure whose left-divisibility order is the given order.

Multiplicability conjecture for finitary upho lattices. Every finitary upho lattice, and in particular every finite-type N\mathbb{N}-graded upho lattice, is multiplicable.

The Petersen counterexample is not a lattice, so it does not settle this restricted claim. The conjecture is connected with the classification of upho lattices by finite graded cores and would imply finiteness of the collection of upho lattices associated with a fixed core.

Sources & referencesView supporting material

Primary source

Ryunosuke Matsuoka, “A Non-Multiplicable Upho Poset Constructed from the Petersen Graph”, arXiv:2606.17549 (2026).

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