“…In recent years, there has been a great deal of interest in creating structured neural network layers that define implicit relationships between their inputs and outputs. For instance, such layers have been created for SAT solving (Wang et al, 2019), ordinary differential equations (Chen et al, 2018), normal and extensive-form games (Ling et al, 2018), rigid-body physics (de Avila Belbute-Peres et al, 2018), sequence modeling (Bai et al, 2019), and various classes of optimization problems Donti et al, 2017;Djolonga & Krause, 2017;Tschiatschek et al, 2018;Wilder et al, 2018;Gould et al, 2019). (Interestingly, softmax, sigmoid, and ReLU layers can also be viewed as implicit layers (Amos, 2019), though in practice it is more efficient to use their explicit form.)…”