YaelDillies/APAP
Source indexedlemma · leanprover/lean4:v4.32.0
curlog_mul_le
APAP.FiniteField · APAP/FiniteField.lean:80 to 90
Mathematical statement
Exact Lean statement
lemma curlog_mul_le (hx₀ : 0 < x) (hx₁ : x ≤ 1) (hy₀ : 0 < y) (hy₁ : y ≤ 1) :
𝓛 (x * y) ≤ x⁻¹ * 𝓛 yComplete declaration
Lean source
Full Lean sourceLean 4
lemma curlog_mul_le (hx₀ : 0 < x) (hx₁ : x ≤ 1) (hy₀ : 0 < y) (hy₁ : y ≤ 1) : 𝓛 (x * y) ≤ x⁻¹ * 𝓛 y := by suffices h : log x⁻¹ - (x⁻¹ - 1) ≤ (x⁻¹ - 1) * log y⁻¹ by rw [← sub_nonneg] at h ⊢ convert h using 1 rw [mul_inv, log_mul] any_goals positivity ring calc log x⁻¹ - (x⁻¹ - 1) ≤ 0 := sub_nonpos.2 <| log_le_sub_one_of_pos <| by positivity _ ≤ (x⁻¹ - 1) * log y⁻¹ := mul_nonneg (sub_nonneg.2 <| (one_le_inv₀ hx₀).2 hx₁) <| by bound