“…Early work here focused on blow-ups in points and on exploiting structural properties of quantum cohomology such as the Witten--Dijkgraaf--Verlinde--Verlinde (WDVV) equations and reconstruction theorems [Gat96, GP98, Gat01]. Subsequent approaches used symplectic methods pioneered by Li–Ruan [LR01, HLR08, Hu00, Hu01], or the Degeneration Formula following Maulik–Pandharipande [MP06, HHKQ18, CDW20], or a direct analysis of the moduli spaces involved and virtual birationality arguments [Man12, Lai09, AW18]. In each case, the aim was to prove ‘birational invariance’: that certain specific Gromov–Witten invariants remain invariant under blow-up.…”