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The Herbrand topos

Published online by Cambridge University Press:  04 June 2013

BENNO VAN DEN BERG*
Affiliation:
Mathematisch Instituut, Utrecht University, PO. Box 80010, 3508 TA Utrecht, The Netherlands. e-mail: B.vandenBerg1@uu.nl

Abstract

We define a new topos, the Herbrand topos, inspired by the modified realizability topos and our earlier work on Herbrand realizability. We also introduce the category of Herbrand assemblies and characterise these as the ¬¬-separated objects in the Herbrand topos. In addition, we show that the category of sets is included as the category of ¬¬-sheaves and prove that the inclusion functor preserves and reflects validity of first-order formulas.

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 2013 

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