-- Mathlib/MeasureTheory/Function/LpSeminorm/CompareExp.lean
theorem eLpNorm_le_eLpNorm_mul_rpow_measure_univ {p q : ℝ≥0∞} (hpq : p ≤ q)
    (hf : AEStronglyMeasurable f μ) :
    eLpNorm f p μ ≤ eLpNorm f q μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Proof state:
case pos
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : q = ⊤
⊢ eLpNorm f p μ ≤ eLpNormEssSup f μ * μ Set.univ ^ p.toReal⁻¹

Tactic:
by_cases hp_top : p = ∞

Result:
case pos
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : q = ⊤
hp_top : p = ⊤
⊢ eLpNorm f p μ ≤ eLpNormEssSup f μ * μ Set.univ ^ p.toReal⁻¹

case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : q = ⊤
hp_top : ¬p = ⊤
⊢ eLpNorm f p μ ≤ eLpNormEssSup f μ * μ Set.univ ^ p.toReal⁻¹

Proof state:
case neg.e_a.e_a
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : q = ⊤
hp_top : ¬p = ⊤
hp_pos : 0 < p.toReal
⊢ 1 / p.toReal = p.toReal⁻¹

Tactic:
exact one_div _

Result:
no goals

Proof state:
case pos
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p = 0
⊢ eLpNorm f p μ ≤ eLpNorm f q μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Tactic:
simp [hp0, zero_le]

Result:
no goals

Proof state:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : q = ⊤
hp_top : ¬p = ⊤
⊢ eLpNorm f p μ ≤ eLpNormEssSup f μ * μ Set.univ ^ p.toReal⁻¹

Tactic:
rw [eLpNorm_eq_eLpNorm' hp0 hp_top]

Result:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : q = ⊤
hp_top : ¬p = ⊤
⊢ eLpNorm' f p.toReal μ ≤ eLpNormEssSup f μ * μ Set.univ ^ p.toReal⁻¹

Proof state:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : ¬q = ⊤
hp_lt_top : p < ⊤
hp_pos : 0 < p.toReal
⊢ eLpNorm f p μ ≤ eLpNorm f q μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Tactic:
rw [eLpNorm_eq_eLpNorm' hp0_lt.ne.symm hp_lt_top.ne, eLpNorm_eq_eLpNorm' hq0_lt.ne.symm hq_top]

Result:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : ¬q = ⊤
hp_lt_top : p < ⊤
hp_pos : 0 < p.toReal
⊢ eLpNorm' f p.toReal μ ≤ eLpNorm' f q.toReal μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Proof state:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
⊢ eLpNorm f p μ ≤ eLpNorm f q μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Tactic:
have hp0_lt : 0 < p := lt_of_le_of_ne (zero_le _) hp0.symm

Result:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
⊢ eLpNorm f p μ ≤ eLpNorm f q μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Proof state:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
⊢ eLpNorm f p μ ≤ eLpNorm f q μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Tactic:
by_cases hq_top : q = ∞

Result:
case pos
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : q = ⊤
⊢ eLpNorm f p μ ≤ eLpNorm f q μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : ¬q = ⊤
⊢ eLpNorm f p μ ≤ eLpNorm f q μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Proof state:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : ¬q = ⊤
hp_lt_top : p < ⊤
⊢ eLpNorm f p μ ≤ eLpNorm f q μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Tactic:
have hp_pos : 0 < p.toReal := ENNReal.toReal_pos hp0_lt.ne' hp_lt_top.ne

Result:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : ¬q = ⊤
hp_lt_top : p < ⊤
hp_pos : 0 < p.toReal
⊢ eLpNorm f p μ ≤ eLpNorm f q μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Proof state:
case pos
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : q = ⊤
hp_top : p = ⊤
⊢ eLpNorm f p μ ≤ eLpNormEssSup f μ * μ Set.univ ^ p.toReal⁻¹

Tactic:
simp only [hp_top, ENNReal.rpow_zero, mul_one, ENNReal.top_toReal, sub_zero,
  GroupWithZero.inv_zero, eLpNorm_exponent_top]

Result:
case pos
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : q = ⊤
hp_top : p = ⊤
⊢ eLpNormEssSup f μ ≤ eLpNormEssSup f μ

Proof state:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : ¬q = ⊤
hp_lt_top : p < ⊤
hp_pos : 0 < p.toReal
⊢ eLpNorm' f p.toReal μ ≤ eLpNorm' f q.toReal μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Tactic:
have hpq_real : p.toReal ≤ q.toReal := ENNReal.toReal_mono hq_top hpq

Result:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : ¬q = ⊤
hp_lt_top : p < ⊤
hp_pos : 0 < p.toReal
hpq_real : p.toReal ≤ q.toReal
⊢ eLpNorm' f p.toReal μ ≤ eLpNorm' f q.toReal μ * μ Set.univ ^ (1 / p.toReal - 1 / q.toReal)

Proof state:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : q = ⊤
hp_top : ¬p = ⊤
⊢ eLpNorm' f p.toReal μ ≤ eLpNormEssSup f μ * μ Set.univ ^ p.toReal⁻¹

Tactic:
have hp_pos : 0 < p.toReal := ENNReal.toReal_pos hp0_lt.ne' hp_top

Result:
case neg
α : Type u_1
E : Type u_2
m : MeasurableSpace α
inst✝ : NormedAddCommGroup E
μ : Measure α
f : α → E
p q : ℝ≥0∞
hpq : p ≤ q
hf : AEStronglyMeasurable f μ
hp0 : p ≠ 0
hp0_lt : 0 < p
hq0_lt : 0 < q
hq_top : q = ⊤
hp_top : ¬p = ⊤
hp_pos : 0 < p.toReal
⊢ eLpNorm' f p.toReal μ ≤ eLpNormEssSup f μ * μ Set.univ ^ p.toReal⁻¹