English
The nonnegative sections form a basis in the (nonunital) C*-algebra context.
Русский
Нелокальные разделы, неотрицательные, образуют базис в контексте нелокальной C*-алгебры.
LaTeX
$$$$ \text{IsBasis}\bigl( (0 \le x) \wedge (\|x\| < 1)\bigr) $$$$
Lean4
/-- The sections of positive strict contractions form a filter basis. -/
theorem isBasis_nonneg_sections : IsBasis (fun x : A ↦ 0 ≤ x ∧ ‖x‖ < 1) ({x | · ≤ x})
where
nonempty := ⟨0, by simp⟩
inter {x y} hx
hy := by
peel directedOn_nonneg_ball x (by simpa) y (by simpa) with z hz
exact ⟨by simpa using hz.1, fun a ha ↦ ⟨hz.2.1.trans ha, hz.2.2.trans ha⟩⟩