Functoriality of modified realizability

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• Peter Johnstone (DPMMS, University of Cambridge)
• Friday 03 February 2017, 11:00-12:00
• Computer Science room 245.

If you have a question about this talk, please contact Paul Taylor.

Room 245 not Sloman Lounge

Realizability toposes come in several `flavours’ (ordinary, relative, modified, Herbrand, ...); in most cases, the starting- point is a Schonfinkel algebra (or partial combinatory algebra). Morphisms between Schonfinkel algebras were first studied by John Longley in 1994; thanks to more recent work of Hofstra, Van Oosten and the speaker, we now have a good understanding of how these relate to geometric morphisms between the induced ordinary realizability toposes, and at least a partial understanding of the corresponding question for Herbrand realizability. However, modified realizability has proved more intractable, perhaps because there doesn’t seem to be a clear understanding of what `modified realizability over an arbitrary Schonfinkel algebra’ should actually mean. This talk will survey the present state of our knowledge.

This talk is part of the Theoretical computer science seminar series.

This talk is included in these lists:

• Computer Science Departmental Series
• Computer Science Distinguished Seminars
• Computer Science room 245
• Theoretical computer science seminar
• computer sience

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