Abundances in the Milky Way across five nucleosynthetic channels from 4
  million LAMOST stars
  Large stellar surveys are revealing the chemodynamical structure of the
Galaxy across a vast spatial extent. However, the many millions of
low-resolution spectra observed to date are yet to be fully exploited. We
employ The Cannon, a data-driven approach to estimating abundances, to obtain
detailed abundances from low-resolution (R = 1800) LAMOST spectra, using the
GALAH survey as our reference. We deliver five (for dwarfs) or six (for giants)
estimated abundances representing five different nucleosynthetic channels, for
3.9 million stars, to a precision of 0.05 - 0.23 dex. Using wide binary pairs,
we demonstrate that our abundance estimates provide chemical discriminating
power beyond metallicity alone. We show the coverage of our catalogue with
radial, azimuthal and dynamical abundance maps, and examine the neutron capture
abundances across the disk and halo, which indicate different origins for the
in-situ and accreted halo populations. LAMOST has near-complete Gaia coverage
and provides an unprecedented perspective on chemistry across the Milky Way.
