Algorithm for searching for failed supernovae (for Pi of the Sky network)

There is a theoretically predicted mechanism core-collapse of massive star that might result in no supernovae explosion (no EM counterpart), such process is called failed supernovae. Currently used optical transient (OT) recognition algorithms could easily detect that star changed its brightness, but failed supernovae process would result in previously visible star to disappear. Detecting such process will require different algorithm than used for OTs. Aim of this paper is to show approach to construct such algorithm for Pi of the Sky network (for failed supernovae in our galaxy).