[Home]Almost distributive lattices

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Abbreviation: ADLat

Definition

An almost distributive lattice is a neardistributive lattice L = (L,∨,∧) such that
AD:   v∧[u∨(x∧[y∨(xz)])] ≤ u∨[(x∧[y∨(xz)])∧(v∨(xy)∨(xz))], and
AD:   v∨[u∧(x∨[y∧(xz)])] ≥ u∧[(x∨[y∧(xz)])∨(v∧(xy)∧(xz))].

Morphisms

Let L and M be almost distributive lattices. A morphism from L to M is a function h : LM that is a homomorphism: h(xy) = h(x)∨h(y)  and  h(xy) = h(x)∧h(y).

Some results

Examples

D[d] = (D∪{d'},∨,∧), where D is any distributive lattice and d is an element in it that is split into two elements d,d' using Alan Day's doubling construction.

Properties

Classtype variety
Equational theory
Quasiequational theory
First-order theory undecidable
Congruence distributive yes
Congruence modular yes
Congruence n-permutable no
Congruence regular no
Congruence uniform no
Congruence extension property
Definable principal congruences
Equationally definable principal congruences
Amalgamation property no
Strong amalgamation property no
Epimorphisms are surjective
Locally finite no
Residual size unbounded

Finite members

[Size 1]?:  1
[Size 2]?:  1
[Size 3]?:  1
[Size 4]?:  2
[Size 5]?:  4
[Size 6]?:  
[Size 7]?:  

Subclasses

Distributive lattices

Superclasses

Neardistributive lattices


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Last edited June 6, 2003 9:01 am (diff)
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