  Generalized causal dynamical triangulations (generalized CDT) is a model of
two-dimensional quantum gravity in which a limited number of spatial topology
changes is allowed to occur. We solve the model at the discretized level using
bijections between quadrangulations and trees. In the continuum limit (scaling
limit) the amplitudes are shown to agree with known formulas and explicit
expressions are obtained for loop propagators and two-point functions. It is
shown that from a combinatorial point of view generalized CDT can be viewed as
the scaling limit of planar maps with a finite number of faces and we determine
the distance function on this ensemble of planar maps. Finally, the relation
with planar maps is used to illuminate a mysterious identity of certain
continuum cylinder amplitudes.
