Papers

Elementary Higher Toposes:

  • A Theory of Elementary Higher Toposes:
    We define an elementary higher topos and show it generalizes elemenary toposes and higher toposes.
  • Complete Segal Objects:
    We define an internal version of a higher category and show it has a similar the same characteristics of a higher categories (such as objects, morphisms, composition, …). Then we use it to define univalence.

Foundations of Higher Categories:

  • A Model for the Higher Category of Higher Categories:
    We construct complete Segal spaces which model simplicial spaces, Segal spaces, complete Segal spaces and spaces along with their universal fibrations.
  • Cartesian Fibrations and Representability:
    We introduce a general method to construct fibrations that model functors in reflective subcategories of simplicial spaces. We also show how this comes with a model structure that we can understand very well. Using this new method we can define representable Cartesian fibrations.
  • Yoneda Lemma for Simplicial Spaces:
    We study the theory of left fibrations over simplicial spaces, by showing that left fibrations are fibrant objects in a model structure. We use that to prove the Yoneda lemma for simplicial spaces.
  • An Introduction to Complete Segal Spaces:
    This is a very intuitive introduction to higher category theory via complete Segal spaces. It discusses subjects such as composition, functoriality, adjunctions and colimits.

Applications of Algebraic Topology:

  • RGB image-based data analysis via discrete Morse theory and persistent homology with Ruth Davidson, Chuan Du, Rosemary Guzman, Adarsh Manawa and Christopher Szul:
    We use a code developed at Australian National University that can detect fundamental topological features of a grayscale image and enhance it so that it can also analyze RGB images. As a result we can perform data analysis directly on RGB images representing water scarcity variability as well as crime variability.

Notes & Slides: