This is a seminar series aimed at students, to create a forum for informal discussions between students in algebra, analysis and topology. Therefore all seminars will be at an introductory level, where most, if not all, concepts will be explained.

Feynman invented his diagrams in the 1950s to make sense of certain integrals that are interesting to the physicists but are not analytically defined. Since then, they have been generalized, first by Penrose in the 1970s, into a "Graphical Calculus" that is now indispensable to algebraists and topologists. In this talk, I will first outline Feynman's derivation and state some theorems about "Feynman integrals". I will then try to define the graphical calculus, and give some examples. No physics knowledge will be assumed, and I will also avoid all proofs.