Smooth weak Fano threefolds.

摘要

In this dissertation, we investigate smooth weak Fano varieties with Picard number 2. We only consider those varieties for which both the unique extremal contractions before and after a flop are divisorial, one of which is of type E1, the other of type E2, E3, E4, or E5. We construct a list of possible numerical invariants for these varieties and show which cases are geometrically realizable. If one contraction is of type E2 we find three possible sets of numerical invariants all of which are geometrically realizable. In case E3/E4, we find seven possibilities, four of which are geometrically realizable. In case E5, we again find seven possibilities, five of which are realizable.