Category:Boolean Algebras

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This category contains results about Boolean Algebras.
Definitions specific to this category can be found in Definitions/Boolean Algebras.


Definition 1

A Boolean algebra is an algebraic system $\struct {S, \vee, \wedge, \neg}$, where $\vee$ and $\wedge$ are binary, and $\neg$ is a unary operation.

Furthermore, these operations are required to satisfy the following axioms:

\((\text {BA}_1 0)\)   $:$   $S$ is closed under $\vee$, $\wedge$ and $\neg$             
\((\text {BA}_1 1)\)   $:$   Both $\vee$ and $\wedge$ are commutative             
\((\text {BA}_1 2)\)   $:$   Both $\vee$ and $\wedge$ distribute over the other             
\((\text {BA}_1 3)\)   $:$   Both $\vee$ and $\wedge$ have identities $\bot$ and $\top$ respectively             
\((\text {BA}_1 4)\)   $:$   $\forall a \in S: a \vee \neg a = \top, a \wedge \neg a = \bot$             


Definition 2

A Boolean algebra is an algebraic system $\struct {S, \vee, \wedge, \neg}$, where $\vee$ and $\wedge$ are binary, and $\neg$ is a unary operation.

Furthermore, these operations are required to satisfy the following axioms:

\((\text {BA}_2 0)\)   $:$   Closure:      \(\ds \forall a, b \in S:\) \(\ds a \vee b \in S \)             
\(\ds a \wedge b \in S \)             
\(\ds \neg a \in S \)             
\((\text {BA}_2 1)\)   $:$   Commutativity:      \(\ds \forall a, b \in S:\) \(\ds a \vee b = b \vee a \)             
\(\ds a \wedge b = b \wedge a \)             
\((\text {BA}_2 2)\)   $:$   Associativity:      \(\ds \forall a, b, c \in S:\) \(\ds a \vee \paren {b \vee c} = \paren {a \vee b} \vee c \)             
\(\ds a \wedge \paren {b \wedge c} = \paren {a \wedge b} \wedge c \)             
\((\text {BA}_2 3)\)   $:$   Absorption Laws:      \(\ds \forall a, b \in S:\) \(\ds \paren {a \wedge b} \vee b = b \)             
\(\ds \paren {a \vee b} \wedge b = b \)             
\((\text {BA}_2 4)\)   $:$   Distributivity:      \(\ds \forall a, b, c \in S:\) \(\ds a \wedge \paren {b \vee c} = \paren {a \wedge b} \vee \paren {a \wedge c} \)             
\(\ds a \vee \paren {b \wedge c} = \paren {a \vee b} \wedge \paren {a \vee c} \)             
\((\text {BA}_2 5)\)   $:$   Identity Elements:      \(\ds \forall a, b \in S:\) \(\ds \paren {a \wedge \neg a} \vee b = b \)             
\(\ds \paren {a \vee \neg a} \wedge b = b \)             


Definition 3

A Boolean algebra is an algebraic structure $\struct {S, \vee, \wedge}$ such that:

\((\text {BA} 0)\)   $:$   $S$ is closed under both $\vee$ and $\wedge$             
\((\text {BA} 1)\)   $:$   Both $\vee$ and $\wedge$ are commutative             
\((\text {BA} 2)\)   $:$   Both $\vee$ and $\wedge$ distribute over the other             
\((\text {BA} 3)\)   $:$   Both $\vee$ and $\wedge$ have identities $\bot$ and $\top$ respectively             
\((\text {BA} 4)\)   $:$   $\forall a \in S: \exists \neg a \in S: a \vee \neg a = \top, a \wedge \neg a = \bot$             


The operations $\vee$ and $\wedge$ are called join and meet, respectively.

The identities $\bot$ and $\top$ are called bottom and top, respectively.

Also, $\neg a$ is called the complement of $a$.

The operation $\neg$ is called complementation.