[FOM] Historical notation question
praatika at mappi.helsinki.fi
Wed Feb 25 06:36:02 EST 2004
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).
PhD., Docent in Theoretical Philosophy
Fellow, Helsinki Collegium for Advanced Studies
University of Helsinki
Helsinki Collegium for Advanced Studies
P.O. Box 4
FIN-00014 University of Helsinki
E-mail: panu.raatikainen at helsinki.fi
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