 At the turn of the 19th Century, David Hilbert (1862–1943) presented, in his Grundlagen der Geometrie, Euclidean geometry as an axiomatic subject that did not depend on diagrams for its proofs (Hilbert 1899). This led to a wave of interest in studying axiom systems in mathematics; in particular one wanted to know if the axioms were independent, and which primitives led to the most elegant systems. Edward Vermilye Huntington (1874–1952) was one of the first to examine this issue for the algebra of logic. He gave three axiomatizations of the algebra of logic, showed each set of axioms was independent, and that they were equivalent (see Huntington 1904). In 1933 he returned to this topic with three new sets of axioms, one of which contained the following three equations (1933: 280):