Stone algebra

In mathematics, a Stone algebra or Stone lattice is a pseudocomplemented distributive lattice L in which any of the following equivalent statements hold for all $x,y\in L:$

• $(x\wedge y{)}^{*}=x^{*}\vee y^{*}$;
• $(x\vee y{)}^{**}=x^{**}\vee y^{**}$;
• $x^{*}\vee x^{**}=1$.

They were introduced by Grätzer & Schmidt (1957), and named after Marshall Harvey Stone.

The set $S(L)\stackrel{\mathrm{d}\mathrm{e}\mathrm{f}}{=}\{x^{*}\mid x\in L\}$ is called the skeleton of L. Then L is a Stone algebra if and only if its skeleton S(L) is a sublattice of L.

Boolean algebras are Stone algebras, and Stone algebras are Ockham algebras.

Examples

• The open-set lattice of an extremally disconnected space is a Stone algebra.
• The lattice of positive divisors of a given positive integer is a Stone lattice.

See also

• De Morgan algebra
• Heyting algebra