Math 2.0

Order, lattices, ordered algebraic structures Definition

Completely distributive lattice

Builds on Complete latticeDistributive latticePower set

Definition

Let LL be a complete lattice. Let JJ be a set, let (Kj)j∈J(K_j)_{j \in J} be a family of sets, and let xj,k∈Lx_{j,k} \in L for j∈Jj \in J and k∈Kjk \in K_j. Let FF be the set of choice functions ff on JJ with f(j)∈Kjf(j) \in K_j for every j∈Jj \in J. The lattice LL is completely distributive if for all such data ⋀j∈J⋁k∈Kjxj,k=⋁f∈F⋀j∈Jxj,f(j).\bigwedge_{j \in J} \bigvee_{k \in K_j} x_{j,k} = \bigvee_{f \in F} \bigwedge_{j \in J} x_{j, f(j)}.

Remarks

Example: the power set of a set XX. A point xx lies in ⋂j⋃kxj,k\bigcap_j \bigcup_k x_{j,k} if and only if for each jj there is k=f(j)k = f(j) with x∈xj,f(j)x \in x_{j, f(j)}. This is membership in the right side, where the axiom of choice picks ff. Non-example: the lattice of open subsets of ℝ\R is a frame but not completely distributive. Take J=ℕ≥1J = \N_{\ge 1}, Kj={1,2}K_j = \set{1, 2}, xj,1=(−1/j,1/j)x_{j,1} = (-1/j, 1/j) and xj,2=ℝ∖{0}x_{j,2} = \R \setminus \set{0}. The left side is ℝ\R. Each meet on the right is the interior of an intersection and never contains 00, so the right side is ℝ∖{0}\R \setminus \set{0}. Complete distributivity is self-dual: the condition is equivalent to the same identity with ⋀\bigwedge and ⋁\bigvee exchanged. Every completely distributive lattice is a distributive lattice.

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  1. Complete lattice concept
  2. Distributive lattice concept
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  4. Completely distributive lattice definition

Further reading

  1. Web https://en.wikipedia.org/wiki/Completely_distributive_lattice
About this page
TagW91HFP63SN
URIm2://W91HFP63SN
Kinddefinition
WritingW0 stub
MSC06D10, 06B23
DefinesCompletely distributive lattice
UsesComplete lattice, Distributive lattice, Power set
Changed2 November 2026

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