Lattice theory

Semimodular lattice

In the branch of mathematics known as order theory, a semimodular lattice, is a lattice that satisfies the following condition: Semimodular lawa ∧ b <: a implies b <: a ∨ b. The notation a <: b means that b covers a, i.e. a < b and there is no element c such that a < c < b. An atomistic (hence algebraic) semimodular bounded lattice is called a matroid lattice because such lattices are equivalent to (simple) matroids. An atomistic semimodular bounded lattice of finite length is called a geometric lattice and corresponds to a matroid of finite rank. Semimodular lattices are also known as upper semimodular lattices; the dual notion is that of a lower semimodular lattice. A finite lattice is modular if and only if it is both upper and lower semimodular. A finite lattice, or more generally a lattice satisfying the ascending chain condition or the descending chain condition, is semimodular if and only if it is M-symmetric. Some authors refer to M-symmetric lattices as semimodular lattices. (Wikipedia).

Semimodular lattice
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Related pages

Order theory | Atom (order theory) | Covering relation | Geometric lattice | Saunders Mac Lane | Compact element | Modular lattice | Garrett Birkhoff | Mathematics | Ascending chain condition | Lattice (order) | Duality (order theory) | Matroid | Antimatroid