We prove the rationality of
the Kähler cone and the positivity of the Chern class c2(X) if X is a Calabi–Yau
threefold with Picard number ρ(X) = 2 and has an embedding into a ℙn-bundle over
ℙm in the cases (n,m) = (1,3) and (3,1). The case (n,m) = (2,2) has been done in
the first part of this paper. Moreover, if (n,m) = (3,1), we describe the ‘other’
contraction different from the projection.
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