English
There is a NonnegSpectrumClass for the unital C*-algebra, ensuring nonnegative spectra.
Русский
Существет класс неотрицательного спектра для унитального C*-алгебры, обеспечивающий неотрицательные спектры.
LaTeX
$$NonnegSpectrumClass Real A$$
Lean4
instance instNonnegSpectrumClass : NonnegSpectrumClass ℝ A :=
.of_spectrum_nonneg fun a ha ↦ by
rw [StarOrderedRing.nonneg_iff] at ha
induction ha using AddSubmonoid.closure_induction with
| mem x hx =>
obtain ⟨b, rfl⟩ := hx
exact spectrum_star_mul_self_nonneg
| zero =>
nontriviality A
simp
| add x y x_mem y_mem hx hy =>
rw [← SpectrumRestricts.nnreal_iff] at hx hy ⊢
rw [← StarOrderedRing.nonneg_iff] at x_mem y_mem
exact hx.nnreal_add (.of_nonneg x_mem) (.of_nonneg y_mem) hy