“…Moreover, Ganea et al [12] and Nickel & Kiela [30] introduce the basic operations of neural networks in the Poincaré ball and the Lorentz model respectively. After that, researchers further introduce various types of neural models in hyperbolic space including hyperbolic attention networks [14], hyperbolic graph neural networks [23,6], hyperbolic prototypical networks [26] and hyperbolic capsule networks [9]. Recently, with the rapid development of hyperbolic neural networks, people attempt to utilize them in various downstream tasks such as word embeddings [37], knowledge graph embeddings [7], entity typing [24], text classification [44], question answering [36] and machine translation [14,34], to handle their non-Euclidean properties, and have achieved significant and consistent improvement compared to the traditional neural models in Euclidean space.…”