∀ {σ : Type u_1} {R : Type u_3} [inst : CommRing R] {τ : Type u_4} {S : Type u_5} [inst_1 : CommRing S]
  [inst_2 : Algebra R S] [inst_3 : UniformSpace R] [DiscreteUniformity R] [inst_5 : UniformSpace S]
  [DiscreteUniformity S], MvPowerSeries.subst = MvPowerSeries.eval₂ (algebraMap R (MvPowerSeries τ S))