In abstract algebra, a branch of pure mathematics, an MV-algebra is an algebraic structure with a binary operation ⊕ {\displaystyle \oplus } , a unary operation ¬ {\displaystyle \neg } , and the constant 0 {\displaystyle 0} , satisfying certain axioms. MV-algebras are the algebraic semantics of Łukasiewicz logic; the letters MV refer to the many-valued logic of Łukasiewicz. MV-algebras coincide with the class of bounded commutative BCK algebras.
Definitions An MV-algebra is an algebraic structure ⟨ A , ⊕ , ¬ , 0 ⟩ , {\displaystyle \langle A,\oplus ,\lnot ,0\rangle ,} consisting of
a non-empty set A , {\displaystyle A,}
a binary operation ⊕ {\displaystyle \oplus } on A , {\displaystyle A,}
a unary operation ¬ {\displaystyle \lnot } on A , {\displaystyle A,} and a constant 0 {\displaystyle 0} denoting a fixed element of A , {\displaystyle A,}
which satisfies the following identities:
( x ⊕ y ) ⊕ z = x ⊕ ( y ⊕ z ) , {\displaystyle (x\oplus y)\oplus z=x\oplus (y\oplus z),}
x ⊕ 0 = x , {\displaystyle x\oplus 0=x,}
x ⊕ y = y ⊕ x , {\displaystyle x\oplus y=y\oplus x,}
¬ ¬ x = x , {\displaystyle \lnot \lnot x=x,}
x ⊕ ¬ 0 = ¬ 0 , {\displaystyle x\oplus \lnot 0=\lnot 0,} and
¬ ( ¬ x ⊕ y ) ⊕ y = ¬ ( ¬ y ⊕ x ) ⊕ x . {\displaystyle \lnot (\lnot x\oplus y)\oplus y=\lnot (\lnot y\oplus x)\oplus x.}
By virtue of the first three axioms, ⟨ A , ⊕ , 0 ⟩ {\displaystyle \langle A,\oplus ,0\rangle } is a commutative monoid. Being defined by identities, MV-algebras form a variety of algebras. The variety of MV-algebras is a subvariety of the variety of BL-algebras and contains all Boolean algebras. An MV-algebra can equivalently be defined (Hájek 1998) as a prelinear commutative bounded integral residuated lattice ⟨ L , ∧ , ∨ , ⊗ , → , 0 , 1 ⟩ {\displaystyle \langle L,\wedge ,\vee ,\otimes ,\rightarrow ,0,1\rangle } satisfying the additional identity x ∨ y = ( x → y ) → y . {\displaystyle x\vee y=(x\rightarrow y)\rightarrow y.}
Examples of MV-algebras A simple numerical example is A = [ 0 , 1 ] , {\displaystyle A=[0,1],} with operations x ⊕ y = min ( x + y , 1 ) {\displaystyle x\oplus y=\min(x+y,1)} and ¬ x = 1 − x . {\displaystyle \lnot x=1-x.} In mathematical fuzzy logic, this MV-algebra is called the standard MV-algebra, as it forms the standard real-valued semantics of Łukasiewicz logic. The trivial MV-algebra has the only element 0 and the operations defined in the only possible way, 0 ⊕ 0 = 0 {\displaystyle 0\oplus 0=0} and ¬ 0 = 0. {\displaystyle \lnot 0=0.}
… excerpt ends here. Continue reading the full article.
