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Sequence closedness and completeness without an interval-family premise

Statement

Work in ZFC. Assume the stationary vacuum model and regular non-degenerate stationary spacetime data. Put C=Σ0∩E and B0=C∪S, and assume Hg∣C=0 for the original metric g. Normalize the selected physical end of this actual section to ADM mass one, and assume T∣S≢0. Use the resulting Harrison family with the same normalized Ernst data, pole and single smooth stationary primitive as in the indexed estimates. Throughout, the original reference section is this B0; its adapted topological identification and the physical stationary end chart remain separate.

Fix 0<δ≤1. Use individual admissibility in the sense of the indexed end-estimates supplier, with this fixed background.

For every sequence (qj,Σj) of individually admissible pairs with qj→q∗∈[δ,1], there is a subsequence converging locally smoothly in the interior and smoothly as normal graphs up to S to an individually admissible gq∗-maximal section. Its interior is a global stationary graph, its normalized end has the stated common decay through four derivatives, and it is complete up to its included boundary S. This conclusion requires no family defined at other parameters. For every sufficiently large physical end radius R, the section minus its open physical graph tail is a compact smooth region containing a neighborhood of S, with manifold boundary S⊔G({rphys=R}) and compact positive-boundary-distance trims in the interior. These physical-core and completeness conclusions also hold for every individually admissible section, using its own end constants. No matching of the adapted topological radius with rphys is required.

Facts & Assumptions

[A1]

The background is the stationary vacuum model with all four regular-spacetime conditions. The actual original exterior is C=Σ0∩E, with smooth closure B0=C∪S, and its maximality hypothesis is Hg∣C=0. The selected physical end of this section has the ADM mass-one normalization, and T∣S≢0. These are the same background hypotheses used by the three indexed suppliers in [F1], the smooth primitive in [F4] and the conditional stationary product in [F7]. The original section used for normalization and graphs is B0. Stationary vacuum model and asymptotic normalization Regular non-degenerate stationary vacuum spacetime Spacelike sections, maximality and lapse–shift data Mass-one convention and Harrison denominator

[F1]

Under [A1], the indexed end upper-lapse bounds, uniform smooth horizon graphs and sequence compact estimates apply on any fixed positive parameter interval. For the sequence in the Statement use δ0=δ/2 and the eventual tail in [δ0,1] selected in step 1.1. These estimates are Uniform end estimates indexed only by existing admissible slices, Indexed compact heights and uniform smooth horizon collars and Compact estimates for arbitrary sequences of individually existing slices.

[F3]

Arzela–Ascoli applies componentwise to an equicontinuous bounded family on compact metric sets. Arzelà--Ascoli for real C(K) under Countable Choice and Dependent Choice: compact closure iff equicontinuous and pointwise bounded Work in ZFC with its inherited countable/dependent choice. The Axiom of Choice

[F4]

Apply the additional positive-parameter smooth-global-primitive branch of Asymptotically flat positive-q ends and cylindrical limit to the same regular mass-one construction, actual physical exterior section C with Hg∣C=0, T∣S≢0, pole and normalization used in [F1]. Its actual single smooth primitive is supplied by Closedness, periods and smooth global choice of W0, with (W0)i=O5(r−3) and normalized contraction; no exact radial identity is assumed. In the physical normalized coordinates (tq,xq), this branch gives (gq)00=−1+O5(rq−1), (gq)0i=O5(rq−2) and (gq)ij=δij+O5(rq−1), with a common end and constants for q∈[δ0,1]. This end conclusion does not identify physical and topological reference radii.

[F5]

The common Gaussian collar used by the horizon estimates in [F1] has jointly smooth normal exponential maps Ψq(τ,x)=exp⁡x(q)(τnˉq(x)) and jointly smooth inverse coordinates. These are the common maps of Bounded boost times give a uniform Gaussian collar cone, applied to the same smooth Lorentzian family, uniformly spacelike reference collar, smooth reference normals and signed boundary collars, and fixed Killing boost data used in [F1]. Restrict those background maps to q∈[δ0,1] and the smaller common graph domain in [F1]; their existence does not require candidate sections at other parameters.

[F6]

For totally differentiable Euclidean maps whose images lie in the next map's domain, D(g∘f)(a)=Dg(f(a))∘Df(a). The chain rule for total derivatives: D(g∘ f)(a)=Dg(f(a))∘ Df(a) We apply it repeatedly to the smooth heights and the affine spatial scalings specified in [F2], through order four.

[F7]

Under the regular vacuum and actual-exterior maximality hypotheses in [A1], put C=Σ0∩E and B0=C∪S. The original product theorem gives a connected smooth spherical exterior B0, compact smooth physical truncations B0,R=B0∖{rphys>R}, and the stationary product over C. Separately choose its adapted topological identification y:B0→{∣y∣≥1} and put s=∣y∣. This s is continuous up to S and has S={s=1}, but it is not identified with the physical end radius rphys=∣x∣. The interior limit graph is a diffeomorphism G:C→Σ∗∘. Only on the physical end do we use rq∗=q∗rphys. Remark 1.3: lapse bounds and stationary product Stationary maximal graphs and normalized graph heights

[F8]

Closed bounded subsets of Euclidean space, in particular finite closed intervals and closed annuli in R3, are compact. Heine-Borel in ℝⁿ: with the Euclidean metric a subset of ℝⁿ is compact if and only if it is closed and bounded, and the proof by bisection uses no choice principle; the same holds on the real line Finite products of compact spaces are compact. A product of finitely many compact spaces is compact in the product topology Continuous images of compact spaces are compact, and a continuous real function on a nonempty compact space attains its minimum. A continuous image of a compact space is compact; a continuous real-valued map on a nonempty compact space attains a maximum and a minimum; and a continuous bijection from a compact space to a Hausdorff space is a homeomorphism Finite unions of compact subsets and closed subsets of compact spaces are compact. A closed subspace of a compact space is compact, and a finite union of compact subspaces is compact Compact subsets of a Hausdorff space are closed. In a Hausdorff space a point and a disjoint compact set, and two disjoint compact sets, have disjoint open neighbourhoods; hence every compact subset is closed, and in a compact Hausdorff space the compact subsets are exactly the closed ones The sphere S2 is path connected; path-connected spaces are connected, and a nonempty clopen subset of a connected space is the whole space. For n≥2, the sphere Sⁿ⁻¹ is path-connected and connected Every path-connected space is connected, and every path component lies inside a component For a topological space the following agree: no separation exists, the only clopen subsets are ∅ and X, and every continuous map to the two-point discrete space is constant Metric and topological compactness agree, and ambient open covers may be restricted to the compact subspace before choosing a finite subcover. For a metric space with its metric topology, compactness in the topological sense is compactness in the metric sense, and the two notions of compact subset coincide A subspace is compact exactly when every family of open subsets of the ambient space covering it, indexed or not, has finitely many members covering it Open cover, subcover, and compact topological space; a compact subset is a subspace that is compact in its own right

[F9]

A smooth cutoff η∈Cc∞(R) exists with 0≤η≤1, η=1 on ∣z∣≤1 and η=0 on ∣z∣≥2. The coordinate chain rule in [F6] and the fundamental theorem of calculus on finite intervals give integration of a smooth scalar along each smooth path piece. We apply the resulting bounds to smooth functions and finite piecewise smooth paths in the section. Explicit compactly supported smooth cutoffs The fundamental theorem of calculus and integration by parts

[F10]

Use the complete smooth Hawking field of the common collar for the actual original reference section B0, with jointly smooth boundary-distance coordinates cq(ρ,y) and the Gaussian maps of [F5]. For each retained pair apply Existence and boost-coordinate description of Hawking-flow heights with its lower parameter bound δ0∈(0,1), q=qj, and original reference section Σ1=B0, using the same stationary product, mass-one normalization and complete collar field. Individual admissibility supplies the connected smooth spacelike maximal candidate with boundary S, smooth boundary extension and global stationary interior graph. Its normalized end decay gives Du~j→0; the compact-core exterior condition required by that fixed-parameter result is proved locally for each such pair in steps 1.1–5.1 below, using individual end decay, the background metric bounds in [F4], original compact truncations in [F7] and the ordinary boundary collar in [F14]. This verification uses no candidate Hawking height, uniform candidate collar estimate or limiting section. Consequently, for every x∈V∖S there is exactly one real vj(x) with ϕvj(x)Kx∈Σj, and this height is individually smooth up to S. The indexed height supplier Indexed compact heights and uniform smooth horizon collars gives one common bound ∣vj∣≤C on a common closed source collar 0≤ρ≤a inside V. Then Φj(x)=ϕvj(x)Kx is the smooth spacelike flow-graph embedding there. The Gaussian-flow input gives c1ρ≤R≤c2ρ and ∣τ∣≤θR with c1,c2>0 and θ<1 common to all supplied pairs. For 0<b<c1a/2, the proper-projection and one-sheet inputs identify its part over 0<R<b as one smooth normal graph. They apply separately to each supplied pair with the same constants, including repeated parameters; no candidate at an unrepresented parameter is required. Lemma 3.3: common spacelike reference collar Bounded boost times give a uniform Gaussian collar cone Radial comparison gives proper normal projection onto a fixed target collar A one-sheet boundary germ propagates across the common normal collar

[F11]

Use only the candidate-independent original-background conclusion of the boundary-angle result: there is a fixed original normal tube Ξ(y,u,v) with K=κ(v∂u+u∂v) and a smooth bounded original reference graph x(r,y)=Ξ(y,rsinh⁡A(r,y),rcosh⁡A(r,y)), where A is rapidity and κ>0. This input does not assume candidate sections or their height bounds. The original event-boundary quadrant input identifies the original exterior in its reference normal frame; the future/outward boost to the invariant frame preserves the exterior wedge v>∣u∣. Local uniqueness of integral curves identifies finite boost segments in this tube with the complete collar flow. Boundary angle bound and normal-graph cone Smooth transverse horizon branches are the null axes of the normal tube Local existence, uniqueness, and smooth dependence for manifold integral curves

[F12]

Every bounded real sequence has a convergent subsequence. For the compact surface coordinates use a fixed smooth identification S≅S2⊂R3, and apply this successively to its three bounded coordinates and to bounded real flow time and source radius. Closed interval inequalities and the sphere equation are preserved on taking limits. Bolzano-Weierstrass: every bounded real sequence has a convergent subsequence

[F13]

Continuous real functions on closed finite intervals are Riemann integrable. For two integrable functions the absolute difference of their integrals is bounded by the interval length times a uniform bound for their difference. The fundamental theorem applies to each smooth candidate derivative along a coordinate segment in its open chart. We use these facts to identify the componentwise compactness limits as successive derivatives; on boundary half-boxes first work in the interior and pass to the boundary by continuity. A continuous function on [a,b] is Riemann integrable, by Heine-Cantor and Riemann's criterion Uniformly close integrable functions have integrals differing by at most the interval length times their uniform error The fundamental theorem of calculus and integration by parts

[F14]

Under Countable Choice, every smooth manifold with boundary has a smooth collar. Apply this to each already supplied smooth section separately; ZFC in [F3] supplies Countable Choice. Since its boundary S is compact, restricting the collar to a smaller closed parameter interval gives a compact embedded collar with compact outer face by [F8]. This is an ordinary collar of that individual manifold, with no uniform width, normal-graph representation or Hawking-height input. Collar neighborhood theorem

Proof

Given: The fixed background in the Statement, including Hg∣C=0, and an arbitrary convergent parameter sequence with individually admissible slices. Goal: Construct the admissible complete limit.

1.1A1F2F4F7givenalgebra

First verify the compact-core condition for the supplied sections without using any indexed candidate estimate or Hawking height. Individual admissibility gives 0<qj≤1. Since qj→q∗≥δ>δ0=δ/2>0, discard a finite prefix so that all retained qj∈[δ0,1]. Fix one retained pair (q,Σ), let G:C→Σ∘ be its stationary graph diffeomorphism, and put s(G(z))=∣y(z)∣ using only the adapted topological coordinates of [F7]. On the separate physical end write r=rphys and v=u~. In xq coordinates the induced metric has components hij=(gq)ij+(gq)0ivj+(gq)0jvi+(gq)00vivj. The individual slope decay from admissibility and the background bounds in [F4] give hij=δij+Oq(rq−1). Hence on some physical graph tail h≥12∑i(dxqi)2, and ∣dr(ξ)∣≤Lqh(ξ,ξ) there, with Lq=2/q. Neither its threshold radius nor this argument uses a candidate lapse bound, a uniform collar or completeness.

2.1F2F6F8F9step 1.1

For every sufficiently large physical radius a, the graph tail Ha=G({r≥a}) is closed in Σ. Its inner sphere and its finite annuli G({a≤r≤b}) are compact and closed by [F8], since their base annuli are compact subsets of C and G is smooth there. Suppose z∈Ha‾Σ∖Ha. Choose a relatively compact convex coordinate ball or boundary half-ball about z, disjoint from the compact inner sphere, and a point w∈Ha in that chart. The coordinate straight segment λ:[0,1]→Σ from w to z stays in the chart and has h-speed bounded by some finite M. Initially it is in the open tail G({r>a}). Until its first exit, the chain rule and integration along every closed initial subsegment, as in [F6] and [F9], give ∣r(λ(t))−r(w)∣≤LqMt. Thus all those points lie in the finite graph annulus G({a≤r≤r(w)+LqM+1}). That compact annulus is closed in Σ, so the first-exit point, including a possible exit at t=1, lies in it. The chart misses its inner sphere, so this point still belongs to the open tail, contradicting first exit. Hence Ha is closed, including against accumulation at S.

3.1F7F8F14step 2.1choose

Take an ordinary closed boundary collar W0=c(S×[0,a0]) in the supplied section using [F14] and [F8]. For all sufficiently large integers n, the closed tails Hn of step 2.1 are nested. Their open complements cover W0: boundary points lie in none of the tails, while each interior point is either outside the physical tail chart or has a finite radius. Compactness of W0 gives one n with W0∩Hn=∅. Consequently G−1(W0∖S) lies in the compact original physical truncation B0,n supplied by [F7]. The continuous topological radius ∣y∣ is bounded on that truncation, so s≤B on W0∖S for some finite B. The compact nonempty outer face L0=c(S×{a0}) is in Σ∘, and its continuous function s>1 has a minimum m>1. No extension of G−1 to S has been used.

4.1F7F8step 3.1choose

Choose 0<ϵ0<m−1 and put J0=G(y−1({1<∣y∣<1+ϵ0})). Radial segments and paths in S2 make J0 connected by [F8]. In the interior manifold the boundary of W0∘=c(S×(0,a0)) is exactly L0, since the compact collar is closed and its other face lies on S. The set J0 misses L0, so J0∩W0∘ is clopen in J0. It is nonempty: fix p∈S and consider c(p,a0/k)→p for integers k≥2. These points have s≤B by step 3.1. If none had s<1+ϵ0, all would belong to the compact interior graph image G(y−1({1+ϵ0≤∣y∣≤B})), closed in the Hausdorff manifold Σ by [F8]. Its boundary limit p cannot lie in that interior image. Thus [F8] gives J0⊂W0∘. This identifies the small topological shell with part of the individual collar without identifying physical and topological radii.

5.1F2F7F8step 1.1step 3.1step 4.1

For any sufficiently large physical radius R, put KR=B0∖{r>R}, compact by [F7]. The set KR∩{∣y∣≥1+ϵ0} is a compact subset of C, so its graph image is compact by [F8]. Step 4.1 places the rest of G(KR∩C) in W0. Therefore Σ∖G({r>R})=S∪G(KR∩C) is contained in the compact union W0∪G(KR∩{∣y∣≥1+ϵ0}). It is closed in Σ because the removed physical graph tail is open in the interior graph, which is open in Σ. It is consequently compact by [F8]; the same argument applies at 2R. With Rq=qR, the normalized end chart identifies the complementary open tail with {∣xq∣>Rq}, and the complement of {rq>2Rq} is also compact. Together with the individual uniform slope limit and the supplied smooth spacelike maximal boundary section, this is precisely the compact-core exterior condition required for [F10]. The argument applies independently to every retained pair before using [F1] or [F10]. For any other individually admissible section at fixed q>0, the same argument uses the background interval [q/2,1] and its own end constants.

6.1A1F1F2F3F13step 1.1step 5.1givenalgebra

The retained tail lies in [δ0,1] by step 1.1, and step 5.1 has independently verified its compact-core exterior condition. Apply all three suppliers in [F1] on this fixed smaller positive interval and the same actual-exterior-maximal background [A1]. Apply [F3] to the resulting uniform finite-order compact stationary estimates, and diagonalize over a countable compact exhaustion and derivative orders. To identify these componentwise limits, write fα for the uniform limit of Dαuj on a smaller coordinate box. For every coordinate segment remaining in that box, [F13] gives Dαuj(x+teℓ)−Dαuj(x)=∫0tDα+eℓuj(x+seℓ) ds. The integrability and uniform integral-error bound in [F13] permit passage to fα(x+teℓ)−fα(x)=∫0tfα+eℓ(x+seℓ) ds. After division by nonzero t, continuity of fα+eℓ makes the right-hand average tend to fα+eℓ(x) as t→0, identifying the corresponding partial derivative. Induction over derivative order therefore identifies all the extracted limits with derivatives of u∗=f0. Using the diagonal extraction at every finite order, obtain one locally smooth stationary height u∗ on the entire reference interior. In original stationary coordinates put Fj=t−uj. Then Nj=1/Dj with Dj=−gj−1(dFj,dFj). The common upper bound Nj≤Cδ0 in [F1] gives Dj≥Cδ0−2>0. Pass to the limit to preserve strict spacelikeness. Mean curvature is continuous in the metric one-jet and graph two-jet, so the smooth limit is maximal. The lower lapse bound in [F1] serves coordinate transversality; it is not used with the wrong reciprocal direction to prove D positive.

6.2A1F1F5F7F8F10F11step 5.1algebra

First establish a background neighborhood captured by the complete K saturation of the source collar in [F10]. In the tube of [F11], choose r∗>0 so that x(r,y) lies in 0≤ρq<a for every q∈[δ0,1] and 0≤r≤r∗; smoothness of the common reference distances and compactness of the parameter interval and S allow this choice. Let A0 bound ∣A(r,y)∣. Choose a closed normal box ∣u∣,∣v∣≤d inside the tube and its original exterior-quadrant neighborhood, and 0<ε<min⁡(r∗,d) with εcosh⁡A0<d. For any exterior point p=Ξ(y,u,v) with 0<v<ε, put r=v2−u2 and ap=arctanh⁡(u/v). Vary rapidity at fixed (r,y) from A(r,y) to ap. Along this finite segment, v=rcosh⁡a≤max⁡(rcosh⁡A(r,y),v(p))<d and ∣u∣<v, so the segment stays in the tube and the exterior. Its tangent is the local K direction with elapsed flow time (ap−A(r,y))/κ. Uniqueness in [F11] identifies it with the complete collar orbit, giving p=ϕsKx(r,y). Thus an ambient neighborhood U of S has its whole exterior part in that saturation. Shrink U inside the common Gaussian domains with all target radii less than b, uniformly in q. For any p∈Σj∘∩U, the representation just constructed has x(r,y)∈V∖S. The compact-core verification in step 5.1 makes the fixed-qj intersection result in [F10] applicable; its uniqueness gives s=vj(x(r,y)), so its indexed height bound yields ∣s∣≤C and p=Φj(x(r,y)). Thus p belongs to the one-sheet normal graph in [F10]; the points of S already lie on its zero-boundary graph. This argument allows arbitrarily large finite ∣s∣ for general exterior points and assumes no candidate at a missing parameter.

7.1F1F2F3F5F10F13step 6.1

On the common horizon collar, [F1] gives uniformly spacelike normal graphs with zero heights on S and uniform finite-order bounds. Use the joint background maps in [F5] and [F10] to express them on a fixed smaller target domain [0,b)×S, and extract a further diagonal subsequence on closed collar charts, retaining the interior subsequence. Apply the derivative-identification argument in step 6.1 using [F13] to these scalar heights on boundary half-boxes: the segment identities hold in their interiors and extend to the closed faces by continuity. Write the resulting smooth convergence as wj→w∗ and set Gj(R,y)=Ψqj(wj(R,y),cqj(R,y)) and G∗(R,y)=Ψq∗(w∗(R,y),cq∗(R,y)). Joint smoothness gives Gj→G∗ smoothly on every smaller closed target collar. Zero boundary values give G∗(0,y)=y, and the uniform spacelike tangent bounds in [F1] make G∗ an embedded smooth spacelike normal graph. This constructs a normal limit; identification with the stationary limit is proved next.

8.1F1F2F5F7F10F12step 6.1step 7.1

Fix 0<R<b and y∈S. By [F10], Gj(R,y)=ϕsjK(cqj(ρj,ηj)) with ∣sj∣≤C and R/c2≤ρj≤R/c1<a/2. Apply [F12] to these two real parameters and the three coordinates of ηj∈S2 to obtain a further subsequence for this fixed point, with limits s∞,ρ∞,η∞. The inequalities give ρ∞>0, and the sphere equation gives η∞∈S. Smoothness of the reference collars and the complete flow gives G∗(R,y)=ϕs∞K(cq∗(ρ∞,η∞))∈E. Thus its candidate approximants converge to an exterior point and their stationary projections eventually lie in one compact interior coordinate neighborhood. Write their stationary coordinates as (tj,xj)→(t∗,x∗). Since tj=uj(xj), local uniform convergence in step 6.1 and continuity give t∗=u∗(x∗). Hence every punctured normal-limit point belongs to the stationary limit. The positive source-radius bound and bounded flow times prevent its projections from escaping to the horizon.

9.1F1F2F5F7F10step 6.1step 7.1step 6.2step 8.1

Conversely, take a smaller common ambient neighborhood of S inside U from step 6.2, with target radii less than some b′<b. Let P=(u∗(x),x) be a stationary-limit point there. Its approximants Pj=(uj(x),x) converge to P by step 6.1 and are eventually captured by step 6.2, so Pj=Gj(Rj,yj). Joint smoothness of the Gaussian inverses gives (τj,Rj,yj)→(τ∗,R∗,y∗) with 0≤R∗<b and τj=wj(Rj,yj). The cone estimate in [F10] passes to ∣τ∗∣≤θR∗. If R∗=0, then τ∗=0 and P=y∗∈S, contrary to P∈E. Therefore R∗>0. Smooth convergence of the normal heights on smaller closed collars gives τ∗=w∗(R∗,y∗), and hence P=G∗(R∗,y∗). Together with step 8.1 this proves both inclusions on an ambient overlap. The normal embedding in step 7.1 therefore attaches the stationary graph smoothly and spacelike to boundary exactly S, excluding additional near-boundary sheets.

10.1F1F2F6step 6.1step 9.1algebra

The positive-q normalized coordinate scalings depend smoothly on q and have common inverses on the fixed positive interval [δ0,1] containing the retained tail and its limit. Put cq=dq/(4q) and y=xq. The normalization in [F2] is u~q(y)=cquq(y/q). Since the spatial scaling is affine and cq is constant in y, repeated application of [F6] gives Dyβu~q(y)=cqq−∣β∣(Dxβuq)(y/q) for ∣β∣≤4. At each fixed normalized end point y, the original points y/qj converge to y/q∗ and lie in a fixed compact interior neighborhood for large j. Local smooth convergence from step 6.1 and continuity of cq therefore give convergence of every derivative in this formula through order four. Pass the uniform end derivative estimates of [F1] to this limit to obtain ∣Dju~∗∣≤Cδ0,jrq∗−3/4−j for j≤4, including its zero height and slope limits. Thus the section is individually admissible at q*.

11.1F1F2F4step 10.1algebra

Work in the normalized end coordinates at q∗. Write r=rq∗, Gμν=(gq∗)μν and v=u~∗. The graph tangent vectors are ∂i+vi∂0, so its induced components are hij=Gij+G0ivj+G0jvi+G00vivj. By [F4] and step 10.1, Gij=δij+O(r−1), G0i=O(r−2), G00=−1+O(r−1) and ∣Dv∣≤Cr−7/4. Hence hij=δij+O(r−1), with constants controlled by the common bounds. Increasing the common radius R gives 12∣ξ∣2≤hijξiξj≤2∣ξ∣2 for every end tangent vector ξ. In particular an end curve has induced length at least its Euclidean radial variation divided by 2.

12.1F2F6F7F8F9step 11.1construct

Construct a physical exhaustion on the original section, rather than estimating derivatives of its unrelated topological radius. Choose a>0 so large that the physical chart, compact truncations of [F7] and end comparison of step 11.1 hold for rphys≥a. With the cutoff in [F9], put F0=a+(1−η(rphys/a))(rphys−a) on the physical tail and F0=a off that tail. The cutoff is identically one for rphys≤a and flat at the join, so these formulas give one smooth nonnegative function on B0, constant near S and equal to rphys for rphys≥2a. Its closed sublevels are compact by the physical-truncation assertion in [F7]. On Σ∗∘ define H=F0∘G−1. Step 11.1 bounds ∣dH∣h=∣drphys∣h in the far tail. On the graph image of the interpolation annulus its norm is bounded by smoothness and compactness; it vanishes over the remaining core. Thus ∣dH∣h≤L throughout the interior for some finite L. Integrating along each smooth path piece using [F6] and [F9] gives ∣H(p)−H(p′)∣≤Llength⁡h(γ) for every interior piecewise smooth path from p to p′.

13.1F2F7F8step 9.1step 12.1

Step 9.1 supplies a closed smaller smooth attached collar W=c(S×[0,b]), with compact outer face Lb=c(S×{b}). These sets are compact by [F8]. The function H has a finite maximum on Lb. Smoothness of the positive metric on the closed collar bounds the lengths of all coordinate segments c(y,[t,b]) uniformly for 0<t≤b. Applying step 12.1 on those interior segments bounds H on W∖S. Therefore G−1(W∖S) lies in one fixed compact sublevel of F0 in B0. The continuous topological radius s is bounded on that sublevel by [F8], so s∘G−1≤A on W∖S. This uses no bound for ∣ds∣h and no boundary extension of G−1.

14.1F7F8step 13.1choose

On the nonempty compact face Lb, the continuous function s∘G−1>1 has a minimum m>1. Choose 0<ϵ<m−1 and put J=G({1<s<1+ϵ}). This is connected by radial paths and paths in the topological S2, using [F8]. In the interior manifold the boundary of W∘=c(S×(0,b)) is exactly Lb, so J∩W∘ is clopen in J. It is nonempty: for fixed y∈S, the collar points c(y,b/n) tend to y and have s∘G−1≤A by step 13.1. If all stayed above 1+ϵ, they would lie in the compact interior image G({1+ϵ≤s≤A}), which is closed in the Hausdorff manifold Σ∗ and cannot contain their boundary limit. Hence [F8] gives J⊂W∘. This captures the small topological shell in the attached collar without identifying it with a physical radial shell.

15.1F2F7F8step 13.1step 14.1

For every sufficiently large physical radius R for which [F7] supplies B0,R, put BΣ,R=S∪G(B0,R∖S)=Σ∗∖G({rphys>R}). Its complement is open, so it is closed in Σ∗. By step 14.1, its part with 1<s<1+ϵ lies in the compact collar W. Its remaining part lies in G(B0,R∩{s≥1+ϵ}), a compact interior image by [F8]. Thus BΣ,R is compact. For sufficiently large R′, step 13.1 places all of W in BΣ,R′, since H=rphys on the far tail and H is bounded on W∖S. This gives a neighborhood of S in BΣ,R′. For any smaller admissible R, remove from that neighborhood the compact interior image of the physical annulus R≤rphys≤R′; what remains is a neighborhood of S contained in BΣ,R. Therefore each physical core contains a neighborhood of S and has no boundary there relative to Σ∗. Away from S the smooth graph diffeomorphism gives its only boundary G({rphys=R}) and its smooth compact-region structure. The boundary of that region as a manifold is S⊔G({rphys=R}). A positive boundary-distance trim is a closed subset of this compact core avoiding S, hence compact in Σ∗∘: the distance is continuous by the triangle inequality and local upper metric bounds in coordinate balls and boundary half-balls, and it vanishes on S by definition.

16.1F2F8F9step 11.1step 12.1step 13.1step 15.1algebra

Choose R′ larger than 2a and the bound for H on the collar in step 13.1. The function P=max⁡{R′,H} on the interior then extends as the constant R′ to a neighborhood of S. It is continuous on the whole section, equals max⁡{R′,rphys} where it varies, and has compact sublevels by step 15.1. To prove the change bound along a piecewise smooth curve, orient it so that its terminal P value is at least its initial value. If P>R′ on the entire curve, integrate the radial bound from step 11.1 using [F9]. Otherwise take the last parameter where P=R′, which exists by continuity and compactness in [F8]. On the final portion P=rphys>R′, and the radial bound gives the terminal value minus R′ at most 2/q∗ times that portion's length, by integration and a limit from its open initial endpoint. Since the initial value is at least R′, this also bounds the net increase. The case of equal endpoint values is immediate. This argument does not differentiate the maximum at a crossing, and also permits parts of the curve through S, where P is locally constant. Taking the infimum over curves gives ∣P(p)−P(p′)∣≤(2/q∗)dh(p,p′). Consequently every intrinsic Cauchy sequence has bounded P and lies in one compact physical core.

17.1F2F8step 9.1step 15.1step 16.1choose

In smaller coordinate balls or boundary half-balls, the smooth positive induced metric has a finite upper bound. Joining nearby points by coordinate line segments inside these convex coordinate sets shows that coordinate convergence implies intrinsic-distance convergence, including at S. The triangle inequality then also makes boundary distance continuous in these coordinates. Its zero set is exactly S: a point outside the compact closed S has a smaller coordinate ball disjoint from S, on which positive lower metric bounds force every path to S to have a positive length before leaving the ball. For any sequence in a compact physical core, compactness gives a point each of whose neighborhoods contains infinitely many sequence terms; otherwise neighborhoods with only finitely many terms would have a finite subcover. Choose increasing indices in shrinking coordinate neighborhoods to obtain an intrinsically convergent subsequence. The Cauchy property from step 16.1 and the triangle inequality give convergence of the entire sequence. This is completeness with the included boundary under [F2].

18.1F1F2F4F7step 6.1step 9.1step 11.1step 15.1step 17.1∎

The physical-core and metric argument above also applies to any individually admissible section at a fixed q>0: its smooth included boundary and global interior graph are part of admissibility, its end derivative decay and the same positive-parameter background bounds give the induced end comparison in step 11.1, and a constant sequence of that pair has the same smooth collar and interior graph as its limits in steps 6.1–9.1. Choose a lower positive parameter bound smaller than q when invoking [F1]. No other section or missing-parameter family is required. Hence each individually admissible section is complete and has these compact physical cores and trims, in addition to the subsequential limiting conclusions already established.

Source notes

Radu’s Section 5.3, Lemma 5.1 gives compact-graph convergence under its own boundary, topology, lapse and height hypotheses. This is background for the present adaptation; the indexed noncompact conclusion is established only by the local argument and declared suppliers.

The actual-exterior maximality premise above specifies this generated conditional result. It is not inferred from maximality of an independently supplied section or from agreement of independent charts, and it is not attributed as a correction to the original article. The immutable original extraction, including Theorem 1.1 and its unresolved source-assessment status, is unchanged.

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External dependencies

Rigidity of stationary black holes with small ADM angular momentum · Section 5.1, equations (5.4)–(5.5); Section 5.2, equations (5.15), (5.22); Section 5.3, Lemma 5.1 and equation (5.24)

In the stated regular stationary vacuum and Harrison setting, Radu discusses lapse and height estimates and proves a compact-graph convergence result used in a continuation argument.

Hypotheses: The source assumes its GR, SBS and maximality conditions, and Lemma 5.1 concerns compact maximal stationary graphs with specified boundary, topology, and uniform lapse and height bounds.

Reading limits: Retained prior source-input or attribution record: Consulted the cited HTML passages in this adjudication. They provide the background and motivation for this adapted statement; they do not assert this item's indexed noncompact strengthening. The numbered local argument uses only the declared suppliers; no independent proof audit of the source is claimed. Fresh maintenance limits: current item and supplier contracts and the local applications were checked; no new reading of the external proof or PDF images is claimed.

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