No slit value has three preimages in the component
ProvedErdos1041.Counterexample.bottleneck_no_three_preimagesdegree-seven-counterexampleerdos-1041polynomial-lemniscate
Under the source’s disk criterion, two-root and unique-critical-point hypotheses, a noncritical value on the slit cannot have three distinct preimages in the critical component.
Preamble
import Definitions.Def_ErdosProblems_Erdos1041_Counterexample_Defs import Definitions.Def_ErdosProblems_Erdos1041_Counterexample_Bottleneck import Mathlib import Mathlib.Algebra.Polynomial.Derivative import Mathlib.Algebra.Polynomial.Div import Mathlib.Algebra.Polynomial.Roots import Mathlib.Analysis.SpecialFunctions.Complex.Log import Mathlib.Analysis.SpecialFunctions.Pow.Real import Mathlib.Analysis.SpecialFunctions.Trigonometric.Basic import Mathlib.Tactic.NormNum import Mathlib.Tactic.Ring import Mathlib.Topology.Connected.LocallyConnected import Mathlib.Topology.EMetricSpace.BoundedVariation open Erdos1041 open Erdos1041.Counterexample noncomputable section open Topology open Erdos1041.Counterexample
Formal statement
theorem Erdos1041.Counterexample.bottleneck_no_three_preimages (p : Polynomial ℂ) (cc : ℂ) (hv : p.eval cc ≠ 0)
(hcover : IsCoveringMap (bottleneckSlitProjection p cc))
(b₁ b₂ : ℂ)
(hb₁ : b₁ ∈ connectedComponentIn (Omega p) cc)
(hb₂ : b₂ ∈ connectedComponentIn (Omega p) cc)
(hr₁ : p.IsRoot b₁) (hr₂ : p.IsRoot b₂)
(hzeros : ∀ w ∈ connectedComponentIn (Omega p) cc, p.IsRoot w → w = b₁ ∨ w = b₂)
(huniq : ∀ c' ∈ connectedComponentIn (Omega p) cc,
(Polynomial.derivative p).IsRoot c' → c' = cc)
(ξ : ℂ) (hξ : ξ ∈ bottleneckSlit (p.eval cc)) (hξv : ξ ≠ p.eval cc)
(w₁ w₂ w₃ : ℂ)
(hw₁ : w₁ ∈ connectedComponentIn (Omega p) cc)
(hw₂ : w₂ ∈ connectedComponentIn (Omega p) cc)
(hw₃ : w₃ ∈ connectedComponentIn (Omega p) cc)
(hp₁ : p.eval w₁ = ξ) (hp₂ : p.eval w₂ = ξ) (hp₃ : p.eval w₃ = ξ)
(n12 : w₁ ≠ w₂) (n13 : w₁ ≠ w₃) (n23 : w₂ ≠ w₃) : False := by sorry
Source
Lean source: https://github.com/wcook04/plectis-erdos-lean/blob/cc7e541cf2081c6fef5a5e377d52e365e33b01eb/ErdosProblems/Erdos1041/Counterexample/Bottleneck.lean#L1188-L1302
Construction by ani: https://www.erdosproblems.com/forum/thread/1041#post-8861
Related paper and provenance: https://github.com/wcook04/plectis-erdos/blob/551bae6dc6e732cf85172d66323c8d2bc77ba962/paper/1041/erdos-1041-lemniscate-newton-flow.tex#L25-L99
Paper prior-art bibliography: https://github.com/wcook04/plectis-erdos/blob/551bae6dc6e732cf85172d66323c8d2bc77ba962/paper/1041/erdos-1041-lemniscate-newton-flow.tex#L1662-L1772
AI-assisted formalization in Will Cook's project; ani is credited for the degree-seven construction. Independent correspondence of the 1958 Problem 5 wording to this modern formulation is unrecorded.