Definition:Lattice (Order Theory)/Definition 2

From ProofWiki
Jump to navigation Jump to search

Definition

Let $\struct {S, \vee, \wedge, \preceq}$ be an ordered structure.


Then $\struct {S, \vee, \wedge, \preceq}$ is called a lattice if and only if:

$(1): \quad \struct {S, \vee, \preceq}$ is a join semilattice

and:

$(2): \quad \struct {S, \wedge, \preceq}$ is a meet semilattice.


That is, for all $a, b \in S$:

$a \vee b$ is the supremum of $\set {a, b}$

and:

$a \wedge b$ is the infimum of $\set {a, b}$


Also see


Sources