diff --git a/Aristotle/Basic.lean b/Aristotle/Basic.lean index 68e65c8..47af439 100644 --- a/Aristotle/Basic.lean +++ b/Aristotle/Basic.lean @@ -1,45 +1,8 @@ import Mathlib -open Filter Set Topology - variable - {๐•œ : Type*} [NontriviallyNormedField ๐•œ] - {E : Type*} [NormedAddCommGroup E] [NormedSpace ๐•œ E] - {f : ๐•œ โ†’ E} {U : Set ๐•œ} + {E : Type*} [NormedAddCommGroup E] [NormedSpace โ„‚ E] -/-- -The singular set of a meromorphic function is countable. --/ -theorem MeromorphicOn.countable_compl_analyticAt [SecondCountableTopology ๐•œ] [CompleteSpace E] - (h : MeromorphicOn f U) : - ({z | AnalyticAt ๐•œ f z}แถœ โˆฉ U).Countable := by - classical - have := discreteTopology_of_codiscreteWithin (eventually_codiscreteWithin_analyticAt f h) - apply countable_of_Lindelof_of_discrete - - -variable - [MeasurableSpace ๐•œ] [SecondCountableTopology ๐•œ] [BorelSpace ๐•œ] - [MeasurableSpace E] [CompleteSpace E] [BorelSpace E] - -/-- -Meromorphic functions are measurable. --/ -theorem meromorphic_measurable {f : ๐•œ โ†’ E} (h : MeromorphicOn f Set.univ) : - Measurable f := by - set s := {z : ๐•œ | AnalyticAt ๐•œ f z} - have hโ‚ : sแถœ.Countable := by simpa using h.countable_compl_analyticAt - have hโ‚‚ : IsOpen s := isOpen_analyticAt ๐•œ f - have hโ‚ƒ : ContinuousOn f s := fun z hz โ†ฆ hz.continuousAt.continuousWithinAt - apply measurable_of_isOpen - intro V hV - rw [(by aesop : f โปยน' V = (f โปยน' V โˆฉ s) โˆช (f โปยน' V โˆฉ sแถœ))] - apply MeasurableSet.union (IsOpen.measurableSet _) (hโ‚.mono inter_subset_right).measurableSet - rw [isOpen_iff_mem_nhds] at * - intro x a - simp_all [mem_setOf_eq, mem_inter_iff, mem_preimage, inter_mem_iff, and_true, s] - apply hโ‚ƒ.continuousAt (hโ‚‚ x a.2) (hV (f x) a.1) - -lemma ฯโ‚€ {r : โ„} {hr : r โ‰  0} {f g : โ„ โ†’ โ„‚} (h : MeromorphicOn f Set.univ) : - Measurable (fun x โ†ฆ f x.1 + g x.2 : โ„ ร— โ„ โ†’ โ„‚) := by +lemma MeromorphicAt.comp {x : โ„} {f : โ„‚ โ†’ E} {g : โ„ โ†’ โ„‚} + (hf : MeromorphicAt f (g x)) (hg : MeromorphicAt g x) : MeromorphicAt (f โˆ˜ g) x := by sorry