Notes on Margulis construction of high-girth 4-regular graphs: pdf (heavily based on the book by Davidoff, Sarnak and Valette).
Here I have notes I typed up for some of the courses I took as an undergrad.
Combinatorics (English) (pdf, changelog)
Notes based on the lectures given by Oriol Serra and Simeon Ball in the fall of 2021.
Advanced undergraduate course in combinatorics. Some sections are incomplete (I'll hopefully come around to fill them someday).
Estructures algebraiques (Catalan) (pdf, changelog)
Notes based on the lectures given by Jordi Guardia in the fall of 2020.
Introduction course to abstract algebra. It does not follow the usual order: it starts with rings, fields, and only at the end introduces groups. (The rationale given by the professor was that rings and fields have more "natural" and "integer-like" properties than groups.)
The second part of the chapter on groups and the last chapter about modules are missing.
Teoria de la probabilitat (Catalan) (pdf, changelog)
Notes based on the lectures given by Anna de Mier in the fall of 2020.
They cover the first half of the course, until the midterm exam.
Matemàtica Discreta (Catalan) (pdf - last updated on 11/06/20)
Notes based on the lectures given by Oriol Serra in the spring of 2020.
It is a first-year undergraduate course that intends to be an introduction to combinatorics/graph theory, but the graph theory part is missing from the notes (there were lots of drawings to be done and I was still afraid of Tikz at the time).
Quantum Physics (English) (pdf - last updated on 20/05/20)
Notes based on the lectures given by Jordi José and Manuel Linares in the fall of 2019.
Introductory course to quantum physics. It presents the historical developments that led to quantum physics, introduces Schrödinger's equation, derives the Hydrogen atom orbitals, and introduces some techniques for dealing with multiple-electron atoms. It does not use bra-ket formalism (this and other basic things are left for a second course for which I have no notes :( ).