# Internal Universes in Models of Homotopy Type Theory

@article{Licata2018InternalUI,
title={Internal Universes in Models of Homotopy Type Theory},
author={Daniel R. Licata and Ian Orton and Andrew M. Pitts and Bas Spitters},
journal={ArXiv},
year={2018},
volume={abs/1801.07664}
}
• Published 23 January 2018
• Mathematics
• ArXiv
We show that universes of fibrations in various models of homotopy type theory have an essentially global character: they cannot be described in the internal language of the presheaf topos from which the model is constructed. We get around this problem by extending the internal language with a modal operator for expressing properties of global elements. In this setting we show how to construct a universe that classifies the Cohen-Coquand-Huber-M\"ortberg (CCHM) notion of fibration from their…

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