[FOM] Historical notation question

[praatika@mappi.helsinki.fi]

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).

Best

Panu


Panu Raatikainen

PhD., Docent in Theoretical Philosophy
Fellow, Helsinki Collegium for Advanced Studies
University of Helsinki
 
Address: 
Helsinki Collegium for Advanced Studies
P.O. Box 4
FIN-00014 University of Helsinki
Finland

E-mail: panu.raatikainen at helsinki.fi
 
http://www.helsinki.fi/collegium/eng/Raatikainen/raatikainen.htm