English
If R is a simple Artinian ring, then R is a semisimple ring.
Русский
Если R простое кольцо с конечной размерностью, то R — полупрямое кольцо.
LaTeX
$$$\\text{IsSimpleRing}(R) \\wedge \\text{IsArtinianRing}(R) \\Rightarrow \\text{IsSemisimpleRing}(R)$$$
Lean4
theorem isSimpleRing_isArtinianRing_iff :
IsSimpleRing R ∧ IsArtinianRing R ↔ IsSemisimpleRing R ∧ IsIsotypic R R ∧ Nontrivial R :=
by
refine ⟨fun ⟨_, _⟩ ↦ ?_, fun ⟨_, _, _⟩ ↦ ?_⟩
on_goal 1 => have := IsSimpleRing.isSemisimpleRing_iff_isArtinianRing.mpr ‹_›
all_goals
simp_rw [isIsotypic_iff_isFullyInvariant_imp_bot_or_top, isFullyInvariant_iff_isTwoSided,
isSimpleRing_iff_isTwoSided_imp] at *
· exact ⟨this, by rwa [and_comm]⟩
· exact ⟨⟨‹_›, ‹_›⟩, inferInstance⟩