  Differentiable Architecture Search (DARTS) has attracted extensive attention
due to its efficiency in searching for cell structures. DARTS mainly focuses on
the operation search and derives the cell topology from the operation weights.
However, the operation weights can not indicate the importance of cell topology
and result in poor topology rating correctness. To tackle this, we propose to
Decouple the Operation and Topology Search (DOTS), which decouples the topology
representation from operation weights and makes an explicit topology search.
DOTS is achieved by introducing a topology search space that contains
combinations of candidate edges. The proposed search space directly reflects
the search objective and can be easily extended to support a flexible number of
edges in the searched cell. Existing gradient-based NAS methods can be
incorporated into DOTS for further improvement by the topology search.
Considering that some operations (e.g., Skip-Connection) can affect the
topology, we propose a group operation search scheme to preserve
topology-related operations for a better topology search. The experiments on
CIFAR10/100 and ImageNet demonstrate that DOTS is an effective solution for
differentiable NAS.
