The countable width-two lattice decomposition conjecture

Let LL be a countable lattice of width two satisfying Whitman's condition, and let NN be a chain order-isomorphic to ω\omega, its dual, or the chain

<2<1<0<1<2<.\dots < -2 < -1 < 0 < 1 < 2 < \dots.

For each iNi\in N, let PiP_i be the disjoint union of two chains AA and BB and the set {0i,1i}\{0_i,1_i\}, such that for every aAa\in A and bBb\in B, a+b=1ia+b=1_i and ab=0iab=0_i.

The countable width-two lattice decomposition conjecture. The lattice LL is semidistributive and

L=iNPi.L=\bigcup_{i\in N}P_i.

Moreover, PiPj={0j,1i}P_i\cap P_j=\{0_j,1_i\} if iji\prec j in NN, and PiPj=P_i\cap P_j=\varnothing otherwise.

This conjecture proposes an explicit description of countable width-two lattices satisfying Whitman's condition; the source suggests that it may follow from a modification of the preceding arguments and may be easier to prove than Jónsson's conjecture. Its resolution is not supplied here.

Sources & referencesView supporting material

Primary source

Brian T. Chan, “A Variation of Galvin and Jónsson's approach to Sublattices of Free Lattices”, arXiv:1510.05285 (2015).

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