[Theory] [Theory Lunch] Nathan Mull, Wednesday 10/19 12:30pm-1:30pm, JCL 298.

[Antares Chen]

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*Date**:* October 19, 2022
*Time: *12:30pm CT
*Location: *JCL 298

*Speaker: *Nathan Mull <https://nmmull.github.io/>

*Title: **Girard’s Paradox: Impredicativity Rears its Ugly Head*

*Zoom: *[link
<https://uchicago.zoom.us/j/93737897802?pwd=a3daMzd1OTNEKzBCbzZYZmNXR2h1QT09>
]

*Abstract:* Girard’s Paradox is often described as a type-theoretic analog
of Russell’s paradox. In essence, it says that if you want to use your type
theory as a logic, there can be no type of all types. But wait, didn’t type
theory come to the rescue in the aftermath of Russell’s paradox? Though,
come to think of it, if we can’t have a set of all sets, why would we think
there could be a type of all types? And you’re telling me Girard’s paradox
applies to systems without a type of all types? Also, what’s type theory?
In this talk, I’ll try to address some of these questions.

[Theory Lunch Webpage
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[Theory Lunch Calendar
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