First off, the department chair, Lei Ni, would like to make it clear that it is not a party, but rather a catered meeting. 

All faculty/staff and graduate students are invited. These meetings normally take place on the terrace of a 12 story building near the math department that sports breathtaking views of the Pacific Ocean or at the Faculty Club.

Aside from the enjoyment of great food (UCSD catering has some pretty delicious selections) and “beverages” (since this is a department funded event, we cannot mention these beverages by name), the day’s activities also include an address by the department chair outlining/recapping the year and introductions/farewells to new/departing members of the faculty or staff.