openAI-math-dataset / lean /OAI /Analysis /BernoulliCone /CompactZeroFiber.lean
roseking's picture
Add lean source and binary files (part 11)
110f4f3 verified
Raw History Blame Contribute Delete
1.12 kB
import OAI.Analysis.BernoulliCone.PositiveTrace
namespace OAI
universe uE
section
noncomputable section
open Set Filter
open scoped Topology
namespace Bernoulli.Foliation
variable {E : Type uE} [TopologicalSpace E]
/-- Compact zero-fiber control. No convergence of the selected root is needed. -/
lemma eventually_near_zero_fiber {K:Set E} (hK:IsCompact K) {f g:E→ℝ} {C:ℝ}
(hf:∀x∈K,ContinuousAt f x) (hg:∀x∈K,ContinuousAt g x)
(hzero:∀x∈K,f x=0 → g x<C) :
∀ᶠ t:ℝ in 𝓝 0,∀x∈K,f x=t → g x<C := by
apply hK.eventually_forall_of_forall_eventually
intro x hx
by_cases hz:f x=0
· have hh:∀ᶠ p:ℝ×E in 𝓝 (0,x),g p.2<C:=
((hg x hx).comp continuous_snd.continuousAt).eventually (gt_mem_nhds (hzero x hx hz))
exact hh.mono fun p hp _=>hp
· have hn:f x-(0:ℝ)≠0:=by simpa using hz
have hh:∀ᶠ p:ℝ×E in 𝓝 (0,x),f p.2-p.1≠0:=
(((hf x hx).comp continuous_snd.continuousAt).sub continuous_fst.continuousAt).eventually_ne hn
exact hh.mono fun p hp he=>False.elim (hp (sub_eq_zero.mpr he))
end Bernoulli.Foliation
end
end
end OAI