 Sheffer has shown that the constants and the 16 operations can be generated as polynomials in just one constant, which can be 0 or 1, and one binary operation, which can be NAND, \(\neg(x\wedge y)\), or NOR, \(\neg(x\vee y)\). Any such sufficient set is called a basis. Along the same lines Stone has shown that conjunction, exclusive-or, and the constant 1 form a basis. The significance of Stone’s basis over Sheffer’s is that Boolean algebras organized with those operations satisfy all the axioms for a commutative ring with identity with conjunction as multiplication and exclusive-or as addition, as well as the law \(x^2 = 1\). Any ring satisfying this last condition is called a Boolean ring. Boolean rings are equivalent to Boolean algebras in the sense that they have the same polynomials.