  Glass transitions are widely observed in various types of soft matter
systems. However, the physical mechanism of these transitions remains
{elusive}, despite years of ambitious research. In particular, an important
unanswered question is whether the glass transition is accompanied by a
divergence of the correlation lengths of the characteristic static structures.
In this study, we develop a deep-neural-network-based method that is used to
extract the characteristic local meso-structures solely from instantaneous
{particle} configurations without any {information} about the dynamics. We
first train a neural network to classify configurations of liquids and glasses
correctly. Then, we obtain the characteristic structures by quantifying the
grounds for the decisions made by the network using Gradient-weighted Class
Activation Mapping (Grad-CAM). We considered two qualitatively different
glass-forming binary systems, and through comparisons with several established
structural indicators, we demonstrate that our system can be used to identify
characteristic structures that depend on the details of the systems. Moreover,
the extracted structures are remarkably correlated with the nonequilibrium
aging dynamics in thermal fluctuations.
