[FOM] Question about Boolean algebras

[Alasdair Urquhart]

I don't know the answer to Neil Tennant's question, but
Garrett Birkhoff's paper "On the Combination of Subalgebras",
(Proceedings of the Cambridge Philosophical Society, Vol. 29,
received 15 May 1933) has the result.  On p. 460, he says:

	Thus  we see that we have reproved the known result

	THEOREM 25.1:  The class of finite Boolean algebras, or
	finite algebras satisfying !-IV and VII, is abstractly 
	identical with the class of finite algebras of point-sets
	with respect to sum, common part and complement.

He doesn't give a reference for who proved it first.