Dear All, We are delighted to present the MaPSS Seminar topic of today, Monday 15/05; please see the abstract below. **This Semester the Seminar will always run on Monday, at 5:00pm in 535A** Following the talk, there will be pizza on offer. Speaker: Gennady Notowidigdo (UNSW) Tetrahedron centres over a general metrical framework Abstract: In this talk, the three main centres of tetrahedra (centroid, circumcentre and Monge point) will be obtained over an arbitrary symmetric bilinear form. I will also talk about the Euler line (unifying the three main centres of a general tetrahedron) and the twelve-point sphere, as well as discuss the existence of orthocentres in a general tetrahedron. Supervisors, please encourage your students to attend. Thanks, MaPSS Organizers