Oral title: Resolving the Inner Edge of HR 8799's Debris Disc with ALMA

Oral abstract: HR 8799 is well known for being the only star to host multiple planets discovered through direct imaging. We have 
observed the system with ALMA and we resolve the inner edge of the cold planetesimal belt. The inner edge is found to be too far 
out to be sculpted by planet b on its current orbit suggesting a complex dynamical history or an extra planet.