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BAR RECURSION AND PRODUCTS OF SELECTION FUNCTIONS

Published online by Cambridge University Press:  13 March 2015

MARTÍN ESCARDÓ
Affiliation:
UNIVERSITY OF BIRMINGHAM, SCHOOL OF COMPUTER SCIENCE, BIRMINGHAM B15 2TT, UK
PAULO OLIVA
Affiliation:
QUEEN MARY UNIVERSITY OF LONDON, SCHOOL OF ELECTRONIC ENGINEERING AND COMPUTER SCIENCE, LONDON E1 4NS, UK

Abstract

We show how two iterated products of selection functions can both be used in conjunction with system T to interpret, via the dialectica interpretation and modified realizability, full classical analysis. We also show that one iterated product is equivalent over system T to Spector’s bar recursion, whereas the other is T-equivalent to modified bar recursion. Modified bar recursion itself is shown to arise directly from the iteration of a different binary product of ‘skewed’ selection functions. Iterations of the dependent binary products are also considered but in all cases are shown to be T-equivalent to the iteration of the simple products.

Type
Articles
Copyright
Copyright © The Association for Symbolic Logic 2015 

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