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Proposition 3.6(1), p. 12 — closure of the hemi-bracket

Proved
CatSymplectic.Hemistrict.proposition_3_6_1

by mikedeng1 · Oct 21, 2026 · Mathlib 0df444a (Lean v4.33.1)

hamiltonian-vector-fieldshemi-bracketmultisymplectic-geometryp2o-batch-pfp2ap2o-gran-per-chapterp2o-plan-paperp2o-v1

For Hamiltonian one-forms F,GF,GF,G, the hemi-bracket is Hamiltonian and its vector field is their vector-field bracket:

d{F,G}h=−ι[vF,vG]ω,v{F,G}h=[vF,vG].d\{F,G\}_h=-\iota_{[v_F,v_G]}\omega,\qquad v_{\{F,G\}_h}=[v_F,v_G].d{F,G}h​=−ι[vF​,vG​]​ω,v{F,G}h​​=[vF​,vG​].

This supplies closure and identifies the field of a nested bracket.

Formalization Note This is the n=2n=2n=2 case on a finite-dimensional real normed space. The paper's ω\omegaω is Ω in Lean.

Preamble
import Mathlib
import Definitions.Def_CatSymplectic_Hemistrict_Basic
Formal statement
namespace CatSymplectic.Hemistrict

theorem proposition_3_6_1 {E : Type*} [NormedAddCommGroup E] [NormedSpace ℝ E]
    [FiniteDimensional ℝ E] (Ω : Form E 3) (hΩ : IsNPlectic 2 Ω)
    (F G : hamSubmodule Ω) :
    hemi Ω F G ∈ hamSubmodule Ω ∧
      IsHamVF Ω (hemi Ω F G)
        (VectorField.lieBracket ℝ (hamVF Ω F) (hamVF Ω G)) ∧
      hamVF Ω (hemi Ω F G) =
        VectorField.lieBracket ℝ (hamVF Ω F) (hamVF Ω G) := by sorry

end CatSymplectic.Hemistrict
Source
Baez, Hoffnung, Rogers, Categorified Symplectic Geometry and the Classical String, arXiv:0808.0246v1, pp. 11–12, Proposition 3.6 part 1, equation (6)
Human review
  • Endorsed by Shuze Chen · Oct 21, 2026

    Confirmed by the moderator at approval.

  • Endorsed by mikedeng1 · Oct 21, 2026

    Confirmed by the mission captain (proposal self-audit).

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