OAI/MathematicalPhysics/Transonic/Exterior/Continuation.lean
1 declarations, 0 contain sorry, 0 declared as axioms
- theorem
OAI.SepticProfile.RegularContinuation.exists_between_lower_equilibriumline 14Source documentation
A strict moving lower fence and an invariant upper equilibrium suffice. An exponential strict upper fence is constructed from the compact Lipschitz constant, rather than assuming a continuation or a separation estimate.
theorem exists_between_lower_equilibrium {a b c d u0 : ℝ} (hab : a≤b) (hcd : c≤d) {f : ℝ×ℝ → ℝ} (hf : ContDiffOn ℝ 1 f (Icc a b ×ˢ Icc c d)) (lo dlo : ℝ → ℝ) (hloder : ∀ t ∈ Icc a b, HasDerivAt lo (dlo t) t) (hlorange : ∀ t ∈ Icc a b, lo t ∈ Icc c d) (hlostrict : ∀ t ∈ Icc a b, dlo t<f (t,lo t)) (heq : ∀ t ∈ Icc a b, f (t,d)=0) (hu0 : lo a≤u0) (hu0d : u0<d) : ∃ u : ℝ → ℝ, u a=u0 ∧ ContinuousOn u (Icc a b) ∧ (∀ t ∈ Icc a b, lo t≤u t ∧ u t<d) ∧ ∀ t ∈ Icc a b, HasDerivWithinAt u (f (t,u t)) (Icc a b) t := by …