“…Important ∃R-completeness results include the realizability of abstract order types [48,59] and geometric linkages [53], as well as the recognition of geometric segment [36,44], unit-disk [34,46], and ray intersection graphs [19]. More results appeared in the graph drawing community [22,23,41,54], regarding the Hausdorff distance [33], regarding polytopes [21,51], the study of Nash-equilibria [6,9,10,25,55], training neural networks [3,8], matrix factorization [20,56,57,58,61], or continuous constraint satisfaction problems [47]. In computational geometry, we would like to mention geometric packing [4], the art gallery problem [2], and covering polygons with convex polygons [1].…”