A rigorous construction of the field of real numbers: the unique (up to isomorphism) completely ordered field with the least upper bound property; along with various formulations of completeness and with a postlude on the measure of sets.
Metropolis is originally created by Matthias Vogelgesang and is available from https://github.com/matze/mtheme as well as CTAN. More information about the theme, including the design principles, can be found at http://bloerg.net/2014/09/20/a-modern-beamer-theme.html. This version demonstrates the use of a progress bar under the frame titles. See the manual for other customisation options.