“…The PPAD-completeness of Nash equilibria was established in [11,18] and extended recently in [36,37]. Over the past decades, a broad range of problems have been proved to be PPAD-hard, including equilibrium computation [1,12,16,21], market equilibrium [9,10,14,15,43], equilibrium in auction [13,25], fair allocation [33], min-max optimization [22] and problems in financial networks [39].…”