Mirror symmetry of Calabi–Yau manifolds can be understood via a Legendre duality
between a pair of certain affine manifolds with singularities called tropical manifolds.
In this article, we study conifold transitions from the point of view of Gross and
Siebert; see [J. Differential Geom. 72 (2006) 169–338], [J. Algebraic Geom. 19 (2010)
679–780] and [Ann. of Math. 174 (2011) 1301–1428]. We introduce the notions of
tropical nodal singularity, tropical conifolds, tropical resolutions and smoothings. We
interpret known global obstructions to the complex smoothing and symplectic small
resolution of compact nodal Calabi–Yau manifolds in terms of certain tropical
–cycles
containing the nodes in their associated tropical conifolds. We prove that the
existence of such cycles implies the simultaneous vanishing of the obstruction to
smoothing the original Calabi–Yau and to resolving its mirror. We formulate a
conjecture suggesting that the existence of these cycles should imply that
the tropical conifold can be resolved and its mirror can be smoothed, thus
showing that the mirror of the resolution is a smoothing. We partially prove
the conjecture for certain configurations of nodes and for some interesting
examples.