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The generic Ricci tensor of the Kerr metric equals the explicit closed-form expression

Proved
KerrBL.ricci_bridge_Kerr

by He Wang · Sep 9, 2026 · Mathlib 0df444a (Lean v4.33.1)

coordinate-geometrygeneral-relativitykerr-metrickerrbl-missionricci-flatness

For all real M,aM,aM,a, every point xxx of the regular domain and all indices b,d∈{0,1,2,3}b,d\in\{0,1,2,3\}b,d∈{0,1,2,3},

Rbd(x)  =  RicciKerr M a b d (r,sin⁡θ,cos⁡θ,Σ,Δ)(x),R_{bd}(x)\;=\;\texttt{RicciKerr}\ M\ a\ b\ d\ \big(r,\sin\theta,\cos\theta,\Sigma,\Delta\big)(x),Rbd​(x)=RicciKerr M a b d (r,sinθ,cosθ,Σ,Δ)(x),

where Rbd=R_{bd}=Rbd​= ricciOf (gKerr M a) (giKerr M a) b d x is the generic derivative-based coordinate Ricci tensor of the specification layer, and RicciKerr is the explicit expression of KerrBL_Kerr_ClosedForms.

This is the bridge from the specification to the explicit expressions whose vanishing Layer III proves. The explicit Ricci expression is never assumed: this theorem derives it from the generic definitions together with the Christoffel bridge and the Christoffel-derivative certification.

Preamble
import Definitions.Def_KerrBL_Kerr_ClosedForms
open KerrBL Filter Topology
Formal statement
theorem KerrBL.ricci_bridge_Kerr (M a : ℝ) (x : Pt) (hx : RegKerr M a x) (b d : Fin 4) :
    ricciOf (gKerr M a) (giKerr M a) b d x = RicciKerr M a b d (x 1) (Real.sin (x 2)) (Real.cos (x 2)) (Sig a (x 1) (Real.cos (x 2))) (Del M a (x 1)) := by sorry
Source
R. P. Kerr, Gravitational field of a spinning mass as an example of algebraically special metrics, Phys. Rev. Lett. 11 (1963) 237-238, https://doi.org/10.1103/PhysRevLett.11.237; R. H. Boyer and R. W. Lindquist, Maximal analytic extension of the Kerr metric, J. Math. Phys. 8 (1967) 265-281, https://doi.org/10.1063/1.1705193, Sec. 2 (Boyer-Lindquist form of the Kerr line element); metric components transcribed token-for-token from the project certificate EinsteinSolver/certificate/kerr/metric.json (sha256 d729883d95fd7d3cf84d9c971c6725f847155562cc4e88660535b8d0bd0be336); design record LEAN/kerr-formalization/mission/DESIGN.md, node N12 (ricci_bridge_Kerr)
Human review
  • Endorsed by Shuze Chen · Sep 14, 2026

  • Endorsed by He Wang · Sep 14, 2026

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

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