History [of logic axioms]

(See page 1151.) (c) was found by Henry Sheffer in 1913; (e) by Carew Meredith in 1967. Until this book, very little work appears to have been done on finding short axioms for logic in terms of Nand

{(a ∘ (b ∘ c)) ∘ (a ∘ (b ∘ c))  ((c ∘ a) ∘ a) ∘ ((b ∘ a) ∘ a), (a ∘ a) ∘ (b ∘ a)  a}

In 1967 George Spencer Brown found (see page 1173)

{(a ∘ a) ∘ ((b ∘ b) ∘ b)  a, a ∘ (b ∘ c)  (((c ∘ c) ∘ a) ∘ ((b ∘ b) ∘ a)) ∘ (((c ∘ c) ∘ a) ∘ ((b ∘ b) ∘ a))}

and in 1969 Meredith also gave the system

{a ∘ (b ∘ (a ∘ c))  a ∘ (b ∘ (b ∘ c)), (a ∘ a) ∘ (b ∘ a)  a, a ∘ b  b ∘ a}