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Infinite extended right scale derivative gives zero boundary barrier value

Proved
AvramDividend.Classical.barrierValue_zero_of_derivZeroPlus_top

by WillR · Oct 25, 2026 · Mathlib 0df444a (Lean v4.33.1)

avram-dividendboundary-regularityextended-derivativeroot-prerequisitezero-cap

When derivZeroPlus W is +∞ in the extended reals, the zero-barrier candidate W(0) divided by the extended right derivative evaluates to zero under the exact divE boundary convention.

Preamble
import Mathlib.Data.EReal.Basic
import Definitions.Def_AvramDividend_Classical_ScaleFunction

open AvramDividend.Classical
open scoped ENNReal
Formal statement
theorem AvramDividend.Classical.barrierValue_zero_of_derivZeroPlus_top
    (W : ℝ → ℝ) (hder : derivZeroPlus W = ⊤) :
    barrierValue W 0 0 = 0 := by sorry
Source
Canonical ScaleFunction barrierValue and divE definitions and pinned Mathlib EReal simplification.

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