English
The support of a Hahn series equals the set of indices with nonzero coefficients; it is well-defined and finite in a suitable sense.
Русский
Опора ряда Хана равна множеству индексов с ненулевыми коэффициентами; она корректна и обладает свойством допустимости/окончательности в нужном смыслe.
LaTeX
$$$\\text{support}(x) = \\{ \\gamma : Γ \\mid x_{\\gamma} \\neq 0 \\}$$$
Lean4
/-- The support of a Hahn series is just the set of indices whose coefficients are nonzero.
Notably, it is well-founded. -/
nonrec def support (x : HahnSeries Γ R) : Set Γ :=
support x.coeff