The countable width-two lattice decomposition conjecture

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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 i∈Ni\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 a∈Aa\in A and b∈Bb\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=⋃i∈NPi.L=\bigcup_{i\in N}P_i.

Moreover, Pi∩Pj={0j,1i}P_i\cap P_j=\{0_j,1_i\} if i≺ji\prec j in NN, and Pi∩Pj=∅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.

References

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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