[FOM] Historical notation question

Neil Tennant neilt at mercutio.cohums.ohio-state.edu
Wed Feb 25 12:30:04 EST 2004

On Wed, 25 Feb 2004 praatika at mappi.helsinki.fi wrote:

> Brian Postow was asking about the origin of the notation \Sigma_i and \Pi_i 
> for the different levels of the arithmetic hierarchy. 
> I don't think that Hirst and Sambin really managed to reply this question. 
> I can't really confirm this now but I am pretty confident that this 
> notation, *for the levels of the arithmetical hierarchy*, is due to John 
> Addison (from the late 1950s).

If it wasn't Addison in the late 1950s, then it might have been Azriel
Levy, `A hierarchy of formulas in set theory.' Memoirs of the American
Mathematical Society, 57. American Mathematical Society, 1965 .

Neil Tennant

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