Cited by 87Geometry and complex manifoldsAlgebraic Geometry and Number TheoryGeometric Analysis and Curvature Flows

Gravitational instantons from rational elliptic surfaces

Open access
Hein, Hans-Joachim·2011·Journal of the American Mathematical Society

Abstract

Let X denote the complex projective plane, blown up at the nine base points of a pencil of cubics, and let D be any fiber of the resulting elliptic fibration on X . Using ansatz metrics inspired by work of Gross-Wilson and a PDE method due to Tian-Yau, we prove that X ∖ D admits complete Ricci-flat Kähler metrics in most de Rham cohomology classes. If D is smooth, the metrics converge to split flat cylinders R + × S 1 × D at an exponential rate. In this case, we also obtain a partial uniqueness result and a local description of the Einstein moduli space, which contains cylindrical metrics whose cross section does not split off a circle. If D is singular but of finite monodromy, they converge at least polynomially to flat T 2 -submersions over flat 2 -dimensional cones that need not be quotients of R 2 . If D is singular of infinite monodromy, their volume growth rates are 4 / 3 and 2 for the Kodaira types I b and I b ∗ , their injectivity radii decay like r − 1 / 3 and ( log ⁡ r ) − 1 / 2 , and their curvature tensors decay like r − 2 and r − 2 ( log ⁡ r ) − 1 . In particular, the I b examples show that a curvature estimate due to Cheeger and Tian cannot be improved in general.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper constructs new complete Calabi–Yau (hyper-Kähler) gravitational instantons on complements of fibers in rational elliptic surfaces, using Tian–Yau Monge–Ampère theory and semi-flat metrics adapted to the elliptic fibration. It proves existence, asymptotic geometry, partial uniqueness for ALH cases, and a moduli count for ALH hyper-Kähler metrics.

Key findings

  • For a rational elliptic surface \(X\), a fiber \(D=f^{-1}(p)\), and \(M=X\setminus D\), Theorem 1.3 gives a complete Calabi–Yau metric \(\omega_{CY}\) with \(\omega_{CY}^2=\alpha\Omega\wedge\Omega\) for all sufficiently large \(\alpha>\alpha_0\), provided the initial Kähler metric has finite energy and vanishes on all bad 2-cycles.
  • Theorem 1.5 classifies asymptotics by the fiber type: if \(D\) is smooth, \(\omega_{CY}\) is ALH\((\ell,\varepsilon,\tau)\) with \(\ell^2\varepsilon=i\alpha\int_D R\wedge R\); if \(D\) is singular with finite monodromy, it is ALG, with generic decay \(\delta=2\) for \(I_0^*\), II, III, IV and \(\delta=4/5,2/3,1/2\) for \(II^*\), \(III^*\), \(IV^*\).
  • For infinite monodromy, the paper obtains new classes: for Kodaira type \(I_b\), \(|B(x_0,s)|\sim s^{4/3}\), \(\operatorname{inj}(x)\sim r(x)^{-1/3}\), \(|Rm|\sim r^{-2}\), and tangent cone \(\mathbb R_+\); for \(I_b^*\), \(|B(x_0,s)|\sim s^2\), \(\operatorname{inj}(x)\sim(\log r(x))^{-1/2}\), \(|Rm|\sim r^{-2}(\log r)^{-1}\), and tangent cone \(\mathbb R^2/\mathbb Z_2\).
  • Theorem 1.9 gives ALH partial uniqueness: if two Ricci-flat ALH 4-manifolds are diffeomorphic to complements of smooth fibers in rational elliptic surfaces and their metrics differ by an exponentially decaying tensor, then the metrics agree. Theorem 1.10 computes the kernel of the linearized Ricci operator modulo Lie derivatives and multiples of \(g\): dimension \(29\), with a 24-dimensional ED subspace and quotient isomorphic to \(\mathfrak{sl}(3,\mathbb R)/\mathfrak{so}(3)\).

Methods

  • The construction uses a noncompact Tian–Yau method for the complex Monge–Ampère equation \((\omega_0+i\partial\bar\partial u)^2=\alpha\Omega\wedge\Omega\), with a complete background Kähler metric \(\omega_0\) built by gluing a given Kähler metric on \(M\) to explicit semi-flat hyper-Kähler metrics near \(D\).
  • The semi-flat metrics are constructed from the elliptic fibration \(f:X\to\mathbb P^1\), Kodaira’s classification of singular fibers, and explicit normal forms for the periods \(\tau_1,\tau_2\); the paper computes their asymptotic geometry and then applies Poincaré/Sobolev and decay estimates for bounded solutions.
  • The uniqueness and moduli results use Hodge theory on manifolds with cylindrical ends, including Fredholm properties of the Laplacian on weighted Hölder spaces and analysis of the Lichnerowicz Laplacian.

Limitations

  • The paper states that Theorem 1.9 is “somewhat unsatisfactory” because it assumes \(\Psi^*g_2-g_1\) is exponentially decaying as a tensor field; it would be desirable to prove this automatically from isometry of the asymptotic cylinders.
  • The paper states that classification issues are deferred elsewhere, that rigorous examples of ALF/ALG/ALH spaces as singularity dilations are still lacking, and that it is unclear which finiteness conditions the folklore conjecture needs.
  • Evident from the text: the existence theorem requires \(\alpha>\alpha_0\), a finite-energy Kähler metric vanishing on bad cycles, and the construction is tied to complements of fibers in rational elliptic surfaces; the ALG decay rates are generic, since “nongeneric ALG spaces may exhibit faster decay.”

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1090/s0894-0347-2011-00723-6

Cites

59 of 59 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

15 of 40 cited sources checked · 4 supported · 2 flagged · accuracy not yet measured

  • Findingcitation

    If B, s, F are defined as in [50] and g denotes the horizontal component of the incomplete semi-flat metric on B, then F|ds|^2 = e^ψ g with ψ∈C∞(B), so that F∼|s|^{-α} for some α>0.

    “Indeed, if we define B, s, F as in [50] and let g denote the horizontal component of the incomplete semi-flat metric on B, then F |ds| 2 = e ψ g with ψ ∈ C ∞ (B), so that F ∼ |s| -α for some α > 0.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [50] Song, Jian, 2007, The Kähler-Ricci flow on surfaces of positive Kodaira dimension, Invent. Math. source

      Section 5.3 defines F on a disk B and studies its behaviour near singular fibres. But Lemma 5.4 (pp. 24–25) gives different behaviours by fibre type: F is bounded for some types and grows logarithmically for type Ib. Those cases contradict the unqualified conclusion that F is comparable to |s|^{-α} for some α>0; the cited passages also do not state the asserted identity with the horizontal metric. (LLM, conf=0.86)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured
  • Interpretationcitation

    The I_b manifolds appear to be the first examples of complete Ricci-flat four-manifolds to saturate the r^{-2} curvature bound from Cheeger-Tian.

    “The I b manifolds appear to be the first examples of complete Ricci-flat fourmanifolds to saturate the r -2 curvature bound from Cheeger-Tian [10].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [10] Cheeger, Jeff, 2006, Curvature and injectivity radius estimates for Einstein 4-manifolds, J. Amer. Math. Soc. source
  • Premisecitation

    If f ∈ C^{2,α}(M) satisfies |f| ≤ C r^{-μ} for some μ > 2, and if β ≤ 2 then ∫(e^f - 1)ω_0^m = 0, then there exists ᾱ ∈ (0,α] and u ∈ C^{4,ᾱ}(M) such that (ω_0 + i∂∂u)^m = e^f ω_0^m; if β ≤ 2, then ∫|∇u|^2 ω_0^m < ∞.

    “Let f ∈ C 2,α (M ) satisfy |f | ≤ Cr -μ for some μ > 2. If β ≤ 2, then assume in addition that (e f -1)ω m 0 = 0. Then there exists an ᾱ ∈ (0, α] and u ∈ C 4, ᾱ(M ) such that (ω 0 + i∂ ∂u) m = e f ω m 0 .If β ≤ 2, then |∇u| 2 ω m 0 < ∞.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [22] Hein, Hans-Joachim, 2010

      Not checked in the free run.

    • cites [23] Hein, Hans-Joachim, 2011, Weighted Sobolev inequalities under lower Ricci curvature bounds, Proc. Amer. Math. Soc. source

      The Introduction (page unavailable) describes a complex Monge–Ampère analogue with the stated condition ∫(e^f−1)ω^m=0 when β≤2 and the regularity f∈C^{2,α} ⇒ u∈C^{4,ᾱ}. It makes that regularity conditional on bounded curvature and scalar-curvature derivatives, which the quoted claim omits. The paper also assumes SOB(β) throughout. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
  • Findingnone given

    ω and ω_sf(α) are not close on their overlap.

    “One issue not present in [20] is that ω and ω sf (α) are not close on their overlap.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [20] Gross, Mark, 2000, Large complex structure limits of 𝐾3 surfaces, J. Differential Geom. source
  • Premisecitation

    For any ALH Riemannian metric g on M, the classes in im(H^2_c(M) -> H^2(M)) are in bijection with the L^2-harmonic 2-forms with respect to g.

    “If g is any ALH Riemannian metric on M , then these classes are in bijection with the L 2 -harmonic 2-forms with respect to g.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [47] Nordström, Johannes, 2008, Deformations of asymptotically cylindrical 𝐺₂-manifolds, Math. Proc. Cambridge Philos. Soc. source

      Theorem 5.10 (p. 15) gives an isomorphism between L²-harmonic forms and the compactly supported classes in de Rham cohomology, which includes degree two. It states this for oriented exponentially asymptotically cylindrical (EAC) manifolds; our copy does not establish the claim for any ALH Riemannian metric. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • Classified as probably not a substantial claim. 21
  • May combine two claims. 76
  • The quote only partly states this claim. 2
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Köhler-Kühnel [32] proves uū = O(r^{-N}) for all N for the Calabi-Yau manifolds in [53].

    “While the present paper was under review, I learned of a recent paper by Köhler-Kühnel [32], which proves uū = O(r -N ) for all N for the Calabi-Yau manifolds in [53].”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [32] Koehler, Bert, 2010, On asymptotics of complete Ricci-flat Kähler metrics on open manifolds, Manuscripta Math. source

      The Introduction (p. 2) says the decay exponent obtained is 1/(6n), calls it too small for the reducible-divisor case, and hopes to improve it. The proof (p. 10) likewise concludes with a decay rate of 1/(6n), not O(r^{-N}) for every N. The arbitrary N mentioned in the construction of the initial metric (p. 4) does not establish the claimed rate for the Ricci-flat metric. (LLM, conf=0.87)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured
    • cites [53] Tian, G., 1990, Complete Kähler manifolds with zero Ricci curvature. I, J. Amer. Math. Soc. source
  • May combine two claims.

    Findingcitation

    The restriction map H^2(X) -> H^2(M) has a 1-dimensional kernel spanned by the Poincaré dual of the fibers, i.e. c1(X), and maps onto the 9-dimensional subspace H^{1,1}(M) ⊂ H^2(M) of classes containing a closed form which is (1,1) with respect to the complex structure of X.

    “More precisely, the restriction map H 2 (X) → H 2 (M ) has a 1-dimensional kernel (spanned by the Poincaré dual of the fibers, i.e. c 1 (X)) and maps onto the 9-dimensional subspace H 1,1 (M ) ⊂ H 2 (M ) of classes containing a closed form which is (1, 1) with respect to the complex structure of X.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [47] Nordström, Johannes, 2008, Deformations of asymptotically cylindrical 𝐺₂-manifolds, Math. Proc. Cambridge Philos. Soc. source

      Split into 2 atoms — 0 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 1 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured
  • May combine two claims.

    Findingcitation

    One way of proving the unobstructedness in Theorem 1.10 is by taking products with T^3 and appealing to Nordström's work on G_2-structures, and the parameter count is consistent with Nordström's Proposition 3.5.

    “One way of proving the unobstructedness in Theorem 1.10 is by taking products with T 3 and appealing to Nordström's work [47] on G 2 -structures.Our parameter count is consistent with [47, Proposition 3.5], though our proof provides a specific bit of extra information concerning Lie derivatives; see also Remark 4.6.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [47] Nordström, Johannes, 2008, Deformations of asymptotically cylindrical 𝐺₂-manifolds, Math. Proc. Cambridge Philos. Soc. source
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Kovalev has sketched a general deformation theory for asymptotically cylindrical Calabi-Yau manifolds, but his parameter count is not entirely accurate and he needs to assume an appropriate analog of the Tian-Todorov theorem, which seems still unknown.

    “Indeed, Kovalev [35] has sketched a general deformation theory for asymptotically cylindrical Calabi-Yau manifolds, similar to Koiso's approach [33] in the compact case.However, his parameter count is not entirely accurate, and he needs to assume an appropriate analog of the Tian-Todorov theorem [51,55], which seems to be still unknown; cf.Corollary 4.3.”
    Quote in the paperNot a substantial claim1 of 4 sources checked
    • cites [35] Kovalev, Alexei, 2006, Ricci-flat deformations of asymptotically cylindrical Calabi-Yau manifolds source

      Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured
    • cites [33] Koiso, N., 1983, Einstein metrics and complex structures, Invent. Math. source
    • cites [51] Tian, Gang, 1987, Smoothness of the universal deformation space of compact Calabi-Yau manifolds and its Petersson-Weil metric source
    • cites [55] Todorov, Andrey N., 1989, The Weil-Petersson geometry of the moduli space of 𝑆𝑈(𝑛≥3) (Calabi-Yau) manifolds. I, Comm. Math. Phys. source
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    According to Table 1, the estimate (3.17) in Song-Tian [50] is incorrect, but the error is irrelevant for the rest of that paper.

    “According to Table 1, the estimate (3.17) in Song-Tian [50] is incorrect, but the error is irrelevant for the rest of that paper.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [50] Song, Jian, 2007, The Kähler-Ricci flow on surfaces of positive Kodaira dimension, Invent. Math. source

      The copy’s Section 3 (pp. 7–8) contains estimates numbered (3.1)–(3.5), but searches for (3.17) did not locate the cited estimate. The copy also does not address whether an error in that estimate would be irrelevant to the rest of the paper. The citing authors attribute their assessment to their own Table 1, which is not evidence available from this source. (LLM, conf=0.76)

      Experimental — accuracy not yet measured
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The method employed in the proof of Lemma 2.2 is due to Grigoryan and Saloff-Coste in much greater generality.

    “The method employed in the proof of Lemma 2.2 is due to Grigoryan and Saloff-Coste [19] in much greater generality.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [19] Grigor’yan, Alexander, 2005, Stability results for Harnack inequalities, Ann. Inst. Fourier (Grenoble) source

      The Introduction (page unavailable) says Grigor’yan and Saloff-Coste provide methods for proving Harnack inequalities, and the overview describes a discretization technique. But the claim does not identify the method used in the citing paper’s Lemma 2.2, so our copy cannot establish that it is the same method or that this paper treats it in greater generality. Searched for the lemma number and descriptions of the proof method. (LLM, conf=0.70)

      Experimental — accuracy not yet measured
  • May combine two claims.

    Findingcitation

    h^1(X, TX) = 8 and h^1(X, TX(log D)) = 9.

    “Moreover, h 1 (X, T X ) = 8 and h 1 (X, T X (log D)) = 9.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [35] Kovalev, Alexei, 2006, Ricci-flat deformations of asymptotically cylindrical Calabi-Yau manifolds source

      The discussion of logarithmic tangent sheaves (p. 13) explains the role of H¹(TW(log D)) but gives neither claimed dimension. Section 6.1 (p. 15) calculates a dimension of 10 for a different example. Searches for the values 8 and 9 alongside the tangent-sheaf terms found no passage establishing the claimed values for X. (LLM, conf=0.73)

      Experimental — accuracy not yet measured
  • May combine two claims.

    Findingnone given

    If D is singular with finite monodromy, then ω_CY is ALG(δ, [θ, ε, τ]) with type I*, and generically the decay rate δ is 2 for I*_0, II, III, IV, and δ is 4/5, 2/3, 1/2 for II*, III*, IV*, though nongeneric ALG spaces may exhibit faster decay.

    “(ii) If D is singular with finite monodromy, then ω CY is ALG(δ, [θ, ε, τ ]) with type I * Generically, the decay rate δ = 2 for I * 0 , II, III, IV, and δ = 4 5 , 2 3 , 1 2 for II * , III * , IV * , but nongeneric ALG spaces may exhibit faster decay.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingcitation

    If the elliptic fibration is isotrivial, then ω_0 is flat and the ALG(δ) decay can be improved to ALG(2 + 1/θ).

    “However, if the elliptic fibration is isotrivial, then ω 0 is indeed flat and we can improve ALG(δ) to ALG(2 + 1 θ ); see also [5].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [5] O. Biquard, V. Minerbe, A Kummer construction for gravitational instantons, Comm. Math. Phys., to appear.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S4 (based).

    Findingnone given

    Up to orientation, there are two bad cycles if the monodromy is trivial, one if the generator of the monodromy is conjugate to (1 b; 0 1), b ∈ N, and none otherwise.

    “Up to orientation, there are two bad cycles if the monodromy is trivial, one if the generator of the monodromy is conjugate to ( 1 b 0 1 ), b ∈ N, and none at all otherwise.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingnone given

    If D is singular with infinite monodromy of Kodaira type I*_b, with monodromy conjugate to -(1 b; 0 1), b ∈ {1,...,4}, then ω_CY satisfies |B(x0,s)| ∼ s^2, inj(x) ∼ |B(x,1)| ∼ (log r(x))^{-1/2}, |Rm| ∼ r^{-2}(log r)^{-1}, |∇^k Rm| ≲ r^{-2-k}(log r)^{-1}, and has a unique tangent cone at infinity given by R^2/Z_2.

    “• Kodaira type I * b , with monodromy conjugate to -( 1 b 0 1 ), where b ∈ {1, ..., 4}: In this case, |B(x 0 , s)| ∼ s 2 for s 1, inj(x) ∼ |B(x, 1)| ∼ (log r(x)) -1/2 for all x, |Rm| ∼ r -2 (log r) -1 , and |∇ k Rm| k r -2-k (log r) -1 for all k ∈ N.Moreover, ω CY has a unique tangent cone at infinity given by R 2 /Z 2 .”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingnone given

    If D is singular with infinite monodromy of Kodaira type I_b, with monodromy conjugate to (1 b; 0 1), b ∈ {1,...,9}, then ω_CY satisfies |B(x0,s)| ∼ s^{4/3}, inj(x) ∼ |B(x,1)| ∼ r(x)^{-1/3}, |Rm| ∼ r^{-2}, |∇^k Rm| ≲ r^{-2-k}, and has a unique tangent cone at infinity given by the half-line R_+.

    “• Kodaira type I b , with monodromy conjugate to ( 1 b 0 1 ), where b ∈ {1, ..., 9}: Then ω CY satisfies |B(x 0 , s)| ∼ s 4/3 for s 1, inj(x) ∼ |B(x, 1)| ∼ r(x) -1/3 for all x, |Rm| ∼ r -2 , and |∇ k Rm| k r -2-k for all k ∈ N.Moreover, ω CY has a unique tangent cone at infinity given by the half-line, R + .”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    For the complete I*b metrics, inj(x) ∼ |B(x,1)| ∼ (log r_x)^{-1/2}.

    “For the same general reason as before, inj(x) ∼ |B(x, 1)| ∼ (log r x ) -1 2 .”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    For Γ=Z2, setting (T,X,Y)=(t^2,x,ty) induces a birational map from (P1_t×E)/Z2 to the surface S: Y^2=T g(X), which is an isomorphism of elliptic fibrations away from t=0,∞.

    “Setting (T, X, Y ) = (t 2 , x, ty) yields a rational map P 1 t × E P 1 T × P 2 XY , which factors through the globally defined Z 2 -action (t, x, y) → (-t, x, -y) and induces a birational map from (P 1 t × E)/Z 2 to the surface S : Y 2 = T g(X), which is in fact an isomorphism of elliptic fibrations away from t = 0, ∞.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    There are two assumptions under which the required Neumann eigenvalue lower bound can be proved: (1) A_i ⊂ B(x_i, ρ_i) with x_i ∈ A_i and ρ_i ∼ r_{i+1}/r_i = o(r_i), and (2) r_{i+1}/r_i ∼ r_i.

    “There are two different assumptions under which we are able to prove (by using Lemmas 2.1-2.2) that this is indeed the case: (1) A i ⊂ B(x i , ρ i ) with x i ∈ A i , ρ i ∼ r i+1r i = o(r i ), and (2) r i+1r i ∼ r i .”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    The main underlying idea works for β ≤ 2 only and strongly relies on the fact that ∫|∇u|^2 < ∞ in this case.

    “The main underlying idea works for β ≤ 2 only and strongly relies on the fact that |∇u| 2 < ∞ in this case.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    In Lemma 3.3(ii), the metrics g_{S,ε} on the base are Kähler, and their Ricci forms are ρ(ω_{S,ε})=-i∂∂ log det(Im Z)=i/4((Im Z)_{ab} dZ_{bc}∧(Im Z)_{cd} dZ_{da}), the pullback of an invariant Kähler metric on H_m under the period map Z.

    “(ii) The metrics g S,ε on the base are Kähler as well.Their Ricci forms ρ(ω S,ε ) = -i∂ ∂ log det(Im Z) = i 4 ((Im Z) ab dZ bc ∧ (Im Z) cd d Zda ), the pullback of an invariant Kähler metric on H m under the period map Z.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    The semi-flat metric is given by (3.8), with Im(τ1τ2)=√3/2 |z|^{5/3}(1-|z|...).

    “ω sf,ε = i|k| 2 Im(τ 1 τ 2 ) ε dz ∧ dz |z| 4 + i 2 ε Im(τ 1 τ 2 ) (dw -Γdz) ∧ (d w -Γdz), (3.8) Im(τ 1 τ 2 ) = √ 3 2 |z| 5 3 (1 -|z|”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    For the complete I*b metrics, as |u_x| tends to 1, r_x is asymptotic to dist_g(u_x,u_x0) and to (1/|u_x|)|log |u_x||^{1/2}.

    “Using notation analogous to our discussion of the I b metrics, (3.18) yields |u x | 1 =⇒ r x ∼ dist g (u x , u x 0 ) ∼ 1 |u x | |log |u x || 1 2”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    Table 1 lists τ1, τ2, N, and the tangent cones of the metrics on the base: incomplete (div(Ω)=0), and complete (div(Ω)=-D).

    “Table 1 lists τ 1 , τ 2 , N, and the tangent cones of the metrics on the base: incomplete (div(Ω) = 0), and complete (div(Ω) = -D).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingreasoning

    In these coordinates, ω_sf,ε = i/2 (du∧dū + ε Im(ζ3) η∧η)(1+O(|u|^{-4m})), with η=dv-Πdu, Π(u,v)=1/u(Pv+Qv), P,Q=O(|u|^{-2m}).

    “ω sf,ε = i 2 (du ∧ dū + ε Im(ζ 3 ) η ∧ η)(1 + O(|u| -4m )), (3.10) η = dv -Π du, Π(u, v) = 1 u ( P v + Qv), P , Q = O(|u| -2m ). (3.11)”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Findingreasoning

    Theorems 1.9 and 1.10 follow from Hodge theory on manifolds with cylindrical ends.

    “Theorems 1.9-1.10follow from Hodge theory on manifolds with cylindrical ends, which is of course a very well-understood subject.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    For a hyper-Kähler ALH manifold (M^4, g), the kernel E of the linearized Einstein operator inside H satisfies E = D ⊕ L_bd, where D = ker Δ_Lich has dimension 34 and L_bd = {L_X g : X = parallel + ED}.

    “Prove that E = D ⊕ L bd , where D = ker Δ Lich has dimension 34 and admits a clear geometric description, whereas L bd = {L X g : X = parallel + ED}.”
    • Also stated in: § Step 2: The kernel of the linearized Einstein operator. · plain
      “The first consequence of this is that D ⊂ ker B| H ; hence E = D ⊕ L bd by (4.2), because wedging a scalar form with ω preserves harmonicity, so that tr h is constant for all h ∈ D, and div h = 0 because bounded harmonic forms are d * -closed.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    For an elliptic fibration U→Δ with a section, U|Δ* ≅ L/Λ for a holomorphic line bundle L and lattice bundle Λ; since H1(Δ*,O*)=0, L≅O and U|Δ* ≅ (Δ*×C)/(Zτ1+Zτ2) for multivalued holomorphic functions τ1,τ2 on Δ*.

    “To explain the notion of monodromy, we begin by noting that U | Δ * ∼ = L/Λ, due to the existence of σ, where L → Δ * is a holomorphic line bundle and Λ ⊂ L is a lattice bundle.Now H 1 (Δ * , O * ) = 0, so L ∼ = O and U | Δ * ∼ = (Δ * × C)/(Zτ 1 + Zτ 2 ) for multivalued holomorphic functions τ 1 , τ 2 on Δ * .”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingnone given

    To close the slit, one twists by the monodromy, which is an isometry in this case.

    “To close the slit, we then simply twist by the monodromy, which is an isometry in this case.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingnone given

    For a degeneration f:U→Δ with I*_b monodromy, the pullback of U|Δ* under z=u^2 extends as an I_{2b} fibration U→Δ_u, and Z2 acts naturally on U such that the quotient has four ordinary double points on its central fiber.

    “For a degeneration f : U → Δ with I * b monodromy, the pullback of U | Δ * under z = u 2 extends as an I 2b fibration U → Δ u , and Z 2 acts naturally on U such that the quotient has four ordinary double points on its central fiber.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    As |z_x| tends to 1, r_x is asymptotic to dist_g(z_x,z_x0) and to |log |z_x||^{3/2}.

    “|z x | 1 =⇒ r x ∼ dist g (z x , z x 0 ) ∼ |log |z x || 3 2 .”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Findingnone given

    Δd is Fredholm of index -(b_r(T^3) + b_{r-1}(T^3)) when acting on weighted Hölder spaces of r-forms with a small enough exponential decay rate, and there are elliptic estimates for Δd on such spaces.

    “Finally, we will need to know that Δ d is Fredholm of index -(b r (T 3 ) + b r-1 (T 3 )) when acting on weighted Hölder spaces of r-forms with a small enough exponential decay rate; also, there are elliptic estimates for Δ d acting on such spaces.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingnone given

    For every z in Δ*, the intrinsic diameter of the fiber f^{-1}(z) and the g-length of the Euclidean circle of radius |z| in Δ* are both asymptotic to |log |z||^{1/2}.

    “For every z ∈ Δ * , the intrinsic diameter of the fiber f -1 (z) and the g-length of the Euclidean circle of radius |z| in Δ * are both ∼ |log |z|| 1 2 .”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    The pullback U of U|Δ* under z=u^6 can be written as (Δ*_u × C_v)/(Z+Zτ(u^6)) and extends to the whole disk Δ_u with central fiber C/(Z+Zζ3).

    “The pullback U of U | Δ * under z = u 6 can be written as (Δ * u × C v )/(Z + Zτ (u 6 )) and thus extends to the whole disk Δ u with central fiber C/(Z + Zζ 3 ).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    If g is Kähler with Ric ≥ 0, then the L^2-harmonics are primitive (1,1); if g is even Kähler with respect to the complex structure of X, then H^{1,1}(M) = R[ω] ⊕ L^2-harmonics.

    “If g is in addition Kähler with Ric ≥ 0, then the L 2 -harmonics are primitive (1, 1) since [Δ d , ω ∧ -] = 0 and because harmonic ED (2, 0)-forms are trivial by the Bochner formula; if g is even Kähler with respect to the complex structure of X, then H 1,1 (M ) = R[ω] ⊕ L 2 -harmonics.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    As r_x tends to infinity, |Θ(x)|^2 = 6π^2 ε^2 b^2 |k(0)|^4 |log |z_x||^{-6} (1+o(1)) and is asymptotic to r_x^{-4}.

    “As r x → ∞, |Θ(x)| 2 = 6π 2 ε 2 b 2 |k(0)| 4 |log |z x || -6 (1 + o(1)) ∼ r -4 x .”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. May combine two claims.

    Findingreasoning

    In the Calabi-Yau setting with dim S=1 and X admitting a holomorphic volume form Ω, Ω defines a faithful pairing ∧^m E⊗T^{1,0}S→C, and using the metric on ∧^m E induced by h_ε one obtains a Riemannian metric g_{S,ε} as before.

    “Calabi-Yau setting.Let dim S = 1 and suppose that X admits a holomorphic volume form Ω. Then Ω defines a faithful pairing ∧ m E ⊗ T 1,0 S → C. Using the metric on ∧ m E induced by h ε , we obtain a Riemannian metric g S,ε as before.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: In the Calabi-Yau setting, dim S=1 and X admits a holomorphic volume form Ω.
  • May combine two claims.

    Findingcitation

    Solving the Monge-Ampère equation changes the metric by O(r^{-2-δ}), by Proposition 2.9, and in actuality by no more than O(r^{-8}).

    “Solving the Monge-Ampère equation changes the metric by O(r -2-δ ), by Proposition 2.9, and in actuality by no more than O(r -8 ); cf.Example 2.10.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Proposition 2.9

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Example 2.10

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingnone given

    In the Gross-Wilson setting where div(Ω)=0, one replaces |z|^{-4} dz∧dz in (3.8) by |z|^{-2} dz∧dz; the semi-flat metric is incomplete, and the metric on the base has a conical singularity with angle 5/6.

    “To conclude, we briefly look at the Gross-Wilson setting, where div(Ω) = 0. We only need to replace |z| -4 dz ∧ dz in (3.8) by |z| -2 dz ∧ dz.The semi-flat metric is incomplete, and the metric on the base has a conical singularity with angle 5 6 .”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingreasoning

    A holomorphic lattice bundle Λ⊂E induces a flat R-linear connection on E, hence an integrable horizontal distribution H on X, and this is independent of the chosen fiber-preserving biholomorphism X≅E/Λ.

    “Choose a fiber-preserving biholomorphism X ∼ = E/Λ for some holomorphic lattice bundle Λ ⊂ E. Then Λ induces a flat R-linear connection on E, hence an integrable horizontal distribution H on X, and this is independent of how we made X ∼ = E/Λ since any two such isomorphisms only differ by a holomorphic section S → Aut(E).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    Blowing down E turns E3 into a (-1)-curve, blowing down E3 turns E2 into a (-1)-curve, and after blowing down E2, the remaining curve E1 becomes a rational cusp curve of self-intersection zero.

    “Blowing down E turns E 3 into a (-1)-curve, blowing down E 3 turns E 2 into a (-1)-curve, and after blowing down E 2 , the remaining curve E 1 becomes a rational cusp curve of self-intersection zero.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    In each case, if |B(x,1)| does not decay too fast, Moser iteration over B(x,1) gives L∞ decay, and derivative bounds follow from Schauder theory.

    “In each case, if |B(x, 1)| does not decay too fast, we then apply Moser iteration over B(x, 1) to get L ∞ decay, based on Lemma 2.1 with α > 1. Derivative bounds follow from Schauder theory, in the setting of Definitions 2.6 and 2.8.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The background manifolds (M,ω0) used in constructing the I_b spaces in Theorem 1.5(iii) are SOB(4/3) and CYL(1/3), with |B(x,1)| decaying only polynomially.

    “We will see in Section 3.3 that these are SOB( 43 ) and CYL( 13 ), with |B(x, 1)| decaying only polynomially.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingnone given

    The injectivity radius satisfies inj(x) ∼ |B(x,1)| ∼ r_x^{-1/3}.

    “As for the injectivity radius, we have inj(x) ∼ |B(x, 1)| ∼ r -1 3 x .”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    If J(0)∈C∖{0,1} and A=-1, then after base change z=u^2 the lifted fibration extends to Δ_u with a smooth central fiber, the quotient has four A1 singularities over z=0, and resolving them gives the normal form with a type I*_0 central fiber.

    “If A = -1, we first make a base change z = u 2 over Δ * z .The lifted fibration U → Δ * u extends to Δ u with a smooth central fiber, D .The free Z 2 -action on U over Δ * u also extends, but with four fixed points on D .The quotient is then an elliptic fibration over Δ z , isomorphic to U over Δ * z , but with four surface singularities of type A 1 over z = 0. Resolving these singularities gives”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingreasoning

    As a corollary of the proof, N in (2.2) could be replaced by the largest number of balls in a shortest ball chain connecting any two points in A.

    “As a corollary of the proof, it is worth noting that N in (2.2) could be replaced by the largest number of balls in a shortest ball chain connecting any two points in A.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingreasoning

    Under the coordinate change z=(u/u0)^{-6}, w=(u/u0)^{-5}v, with u0:=6 4√3 ε^{-1/2}|k(0)|, u ranges over the truncated sector |u|>u0, 0<arg u<2π/6, and v belongs to a fundamental cell in {u}×C that converges to the one spanned by 1, ζ3 as |u|→∞.

    “Here, u ranges over the truncated sector |u| > u 0 , 0 < arg u < 2π 6 , and v belongs to a fundamental cell in {u} × C that converges to the one spanned by 1, ζ 3 as |u| → ∞.”
    Quote in the paperSubstantial claim
  • The quote only partly states this claim.

    Findingreasoning

    For I*_b, U|Δ* = (Δ*×C_v)/(Zτ1+Zτ2) with τ1=1 and τ2=b/(πi) log u.

    “Now, according to what we said about the I 2b case, U | Δ * = (Δ * × C v )/(Zτ 1 + Zτ 2 ) with τ 1 = 1 and τ 2 = b πi log u.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    For Γ=Z2, the resulting elliptic fibration has four sections, given by the (-1)-curves E^2_i and E^3_0, and two singular fibers, both of Kodaira type I*_0.

    “The resulting elliptic fibration then has four sections, given by the (-1)-curves E 2 i and E 3 0 , and two singular fibers.The one at T = 0 consists of a”
    • Also stated in: § 3.1. · plain
      “Both fibers are of Kodaira type I * 0 .”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    The multiplicities of z•Φ along E1,E2,E3,E are 1,2,3,6, whereas the multiplicities of Φ*(dz∧dw) are 1,3,5,10.

    “One checks that the multiplicities of z •Φ along these are 1, 2, 3, 6, whereas the multiplicities of Φ * (dz ∧dw) are 1, 3, 5, 10.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingnone given

    On manifolds asymptotic to R+ × Y, the space of bounded harmonic r-forms modulo ED has dimension ≤ b_r(Y) + b_{r-1}(Y); equality holds for r = 2 in the setting of this paper.

    “Remark 4.2.On manifolds asymptotic to R + × Y , the space of bounded harmonic r-forms modulo ED always has dimension ≤ b r (Y ) + b r-1 (Y ).It is a key point for us (and rather a coincidence) that we have equality for r = 2 in our setting.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    If β>2 is an integer and (M,ω0) is asymptotically a bundle with bounded fibers over a β-dimensional cone with radius function r, then Δ(r^{2-μ}) ≈ (2-μ)(β-μ)r^{-μ}<0 for μ∈(2,β), so |u_ε| ≤ C_μ r^{2-μ} for every μ<β if f∈C∞_0(M).

    “To illustrate the barrier method, suppose that β > 2 is an integer and (M, ω 0 ) is asymptotically a bundle with bounded fibers over a β-dimensional cone with radius function r.Then Δ(r 2-μ ) ≈ (2 -μ)(β -μ)r -μ < 0 if μ ∈ (2, β), so |u ε | ≤ C μ r 2-μ for every μ < β if f ∈ C ∞ 0 (M ).”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: In the barrier method illustration, β>2 is an integer and (M,ω0) is asymptotically a bundle with bounded fibers over a β-dimensional cone with radius function r.
  • May combine two claims.

    Findingreasoning

    Existence of a section is necessary to construct g_{sf,ε}; g_{sf,ε} as a tensor field depends on the choice of section σ; for every smooth section σ there is a vertical translation map T(x)=x+σ(f(x)), and g_{sf,ε}[σ]=T*g_{sf,ε}[σ'] if σ' is holomorphic; T preserves g_{sf,ε} iff σ is tangent to H, which implies σ is holomorphic.

    “Existence of a section is necessary to construct g sf,ε , and g sf,ε as a tensor field depends on the particular choice of a section σ.However, σ also defines a complex Lie group structure on each fiber X s with unit σ(s), so for every smooth section σ there is an associated vertical translation map, T (x) = x + σ (f (x)), and g sf,ε [σ] = T * g sf,ε [σ ] if σ is holomorphic.Also, T preserves g sf”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    If J(0)∈C∖{0,1} and A=1, then τ1,τ2 extend as single-valued functions on Δ, and U≅(Δ×C)/(Zτ1+Zτ2) with D smooth (I0).

    “If A = 1, then τ 1 , τ 2 extend as single-valued functions on Δ, and U ∼ = (Δ × C)/(Zτ 1 + Zτ 2 ) with D smooth (I 0 ).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingcitation

    inj(x) is bounded below by |B(x,1)| from [9, Theorem 4.3] because |Rm| ≤ C, and one easily finds a subset of B(x,1) with sufficient volume.

    “To make this rigorous, note that inj(x) |B(x, 1)| from [9, Theorem 4.3] because |Rm| ≤ C, and one easily finds a subset of B(x, 1) with sufficient volume.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [9, Theorem 4.3]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingown data

    The topological obstruction vanishes; H^2(X|Δ*,Z) is generated by the class of the fibers and by the bad cycles C, for which <ω_sf(α), C> = 0 by computation.

    “We have in fact already set things up in such a way that the topological obstruction vanishes; as we will see, H 2 (X| Δ * , Z) is generated by the class of the fibers and by the bad cycles, C, for which ω sf (α), C = 0 by computation.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    Since N=1, Ω = g dz∧dw with g(z)= z^{-2} k(z) or z^{-1} k(z), and k(0)=0, if div(Ω)=-D or 0, respectively.

    “Since N = 1, we have Ω = g dz ∧ dw with g(z) = z -2 k(z) or z -1 k(z), and k(0) = 0, if div(Ω) = -D or 0, respectively.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    The semi-flat metric g_{sf,ε} and the base metric g_{S,ε} are Kähler, and the volume form of g_{sf,ε} is a constant multiple of Υ^m∧Ῡ^m or Ω∧Ω, so that Hol(X,g_{sf,ε})⊂Sp(m) or SU(m+1).

    “We will see that g sf,ε and g S,ε are in fact Kähler and that the volume form of g sf,ε is a constant multiple of Υ m ∧ Ῡm or Ω ∧ Ω, so that Hol(X, g sf,ε ) ⊂ Sp(m) or SU(m + 1).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    For Γ=Z2, the 2-forms Ω0=dt∧dw and Ω∞=ds∧dw are invariant under the Z2-action; hence they lift to the rational elliptic surface with pole divisor the singular fiber at T=∞,0, respectively.

    “The key fact is that both Ω 0 and Ω ∞ are invariant under the Z 2 -action; hence they lift to the rational elliptic surface with pole divisor the singular fiber at T = ∞, 0, respectively.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Findingnone given

    In the hyper-Kähler setting with dim S=m and X admitting a holomorphic symplectic form Υ such that all fibers X_s are complex Lagrangians, there exists a unique Riemannian metric g_{S,ε} on S, compatible with the complex structure on S, such that the faithful pairing E⊗T^{1,0}S→C given by Υ is isometric with respect to h_ε and the Hermitian metric induced by g_{S,ε}.

    “Hyper-Kähler setting.Let dim S = m and assume that X admits a holomorphic symplectic form Υ such that all X s are complex Lagrangians.Then there exists a unique Riemannian metric g S,ε on S, compatible with the complex structure on S, such that the faithful pairing E ⊗ T 1,0 S → C given by Υ is isometric with respect to h ε and the Hermitian metric induced by g S,ε .”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: In the hyper-Kähler setting, X admits a holomorphic symplectic form Υ such that all fibers X_s are complex Lagrangians.
  • May combine two claims.

    Findingnone given

    In the main application to Theorem 1.3, f = log((αΩ∧Ω)/ω_0^2) is in C∞_0(M), and β ≤ 2 holds.

    “In our main application (Theorem 1.3), f = log((αΩ ∧ Ω)/ω 2 0 ) ∈ C ∞ 0 (M ), but indeed β ≤ 2.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingreasoning

    This recovers the optimal Neumann-Poincaré constant r^2 for annuli A(r, r+1) in R^n up to some bounded factor.

    “In particular, this then recovers the optimal Neumann-Poincaré constant r 2 for annuli of the form A(r, r + 1) in R n up to some bounded factor.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingreasoning

    For Γ=Z3, the resulting singular fiber over T=0 has spine X=0 and three two-component ribs E^1_i∪E^2_i (Kodaira type IV*), while the fiber over T=∞ consists of L1,L2,L3 intersecting in (1:0:0)∈L3 (Kodaira type IV).

    “The resulting singular fiber over T = 0 has a spine-rib structure again, with X = 0 as spine and three two-component ribs E 1 i ∪ E 2 i (Kodaira type IV * ).The fiber over T = ∞ consists of L 1 , L 2 , L 3 , intersecting in (1 : 0 : 0) ∈ L 3 (Kodaira type IV).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    In Corollary 3.4, for an elliptic fibration over a Riemann surface with a holomorphic section and no singular fibers, with Ω a holomorphic symplectic form and ω_{sf,ε} the semi-flat hyper-Kähler metric constructed from σ and Ω/√2 with fiber area ε, one has Ω=g dz∧dw and explicit formulas for ω_{sf,ε} and Γ; the Ricci form of the induced base metric is the pullback of the hyperbolic metric of Gauß曲

    “Corollary 3.4.Let f : X → S be an elliptic fibration over a Riemann surface with a holomorphic section σ and no singular fibers.Let Ω be a holomorphic symplectic form on X.Let ω sf,ε be semi-flat hyper-Kähler constructed from σ, Ω/ √ 2, such that the fibers of f have area ε with respect to ω sf,ε .Thus, in particular, ω 2 sf,ε = Ω ∧ Ω.”
    • Also stated in: § Lemma 3.3. · plain
      “On U , the Ricci form of the induced metric ω S,ε on the base is given by ρ(ω S,ε ) = -i∂ ∂ log Im(τ ) = i 4 dτ ∧ dτ Im(τ ) 2 , the pullback of the hyperbolic metric of Gauß curvature -2 on the upper half-plane H = {Im(τ ) > 0} under the period map τ = τ 2 τ 1 : U → H.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    T*Ω = Ω, so the integrand in ∫(ω0(α,t)^2 - αΩ∧Ω) has compact support.

    “(Notice that T * Ω = Ω, so the integrand here has compact support.)”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    To determine the multiplicity N of Φ*(dz∧dw) along D, it suffices to compute Ψ*Θ=2πi dz∧dw, where Θ:=dz∧(dx/y) has multiplicity zero along D; thus N=0.

    “To determine the multiplicity N of Φ * (dz ∧ dw) along D, it suffices to compute that Ψ * Θ = 2πi dz ∧ dw, where Θ := dz ∧ (dx/y) obviously has multiplicity zero along D. Thus, N = 0.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingnone given

    The fiber over u in Δ+ has diameter asymptotic to |log |u||^{1/2}, and the length of the half-circle of radius |u| in Δ+ is asymptotic to |u|^{-1}|log |u||^{1/2}.

    “since the fiber over u ∈ Δ + has diameter ∼ |log |u|| 1/2 , and the length of the half- circle of radius |u| in Δ + is ∼ |u| -1 |log |u|| 1/2 .”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingcitation

    In Section 3.3, for each model fibration in Kodaira's list, one constructs an explicit isomorphism Φ: U|Δ*→(Δ*×C)/(Zτ1+Zτ2), determines the multiplicity N of Φ*(dz∧dw) along D, and obtains g(z)=z^{-N-1}k(z) or g(z)=z^{-N}k(z), k(0)=0, according to whether div(Ω)=-D or div(Ω)=0.

    “For each member of this list, we then construct an explicit isomorphism Φ : U | Δ * → (Δ * × C)/(Zτ 1 + Zτ 2 ), meaning that both the map Φ and the functions τ 1 , τ 2 will be explicit.This allows us to determine the multiplicity N of Φ * (dz ∧ dw) along D, so that Φ * (dz ∧ dw) = f N h dx ∧ dy with h(p) = 0 in local coordinates (x, y) on U near each point p ∈ D. Thus, we either have g(z) = z -N -”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [29] Kodaira, K., 1963, On compact analytic surfaces. II, III, Ann. of Math. (2) source
    • The authors state this as an assumption: In Section 3.3, D does not contain (-1)-curves and is reduced, equivalently f admits a holomorphic section, equivalently U|Δ*≅(Δ*×C)/(Zτ1+Zτ2).
    • The authors state this as an assumption: In Section 3.3, div(Ω) is either -D (the interesting case on a rational elliptic surface) or 0 (the Gross-Wilson setting).
  • May combine two claims.

    Findingreasoning

    For the complete I*b metrics, the fiber has diameter asymptotic to (log r_x)^{1/2}, whereas the g-length of the half-circle is asymptotic to r_x, i.e. precisely linear in the distance from any fixed base point rather than sublinear.

    “In particular, the fiber has diameter ∼ (log r x ) 1/2 , whereas the g-length of the half-circle is ∼ r x , i.e. precisely linear in the distance from any fixed base point rather than sublinear.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    If J(0)=0, then τ is possibly multivalued but still regular at 0, with τ(0) in the orbit of ζ3; [A] fixes τ(0), yielding six possibilities for A∈SL(2,Z) up to conjugation, including A=±1.

    “If J (0) = 0, then τ is possibly multivalued, but still regular at 0, with τ (0) in the orbit of ζ 3 .[A] fixes τ (0), which in total yields six possibilities for A ∈ SL(2, Z) up to conjugation, including A = ±1.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    Conversely, every linear vector field X0 on C^2/Λ defines a unique linear growth harmonic vector field X on M, and then h = L_X g ∈ D.

    “Conversely, every linear vector field X 0 on C 2 /Λ defines a unique linear growth harmonic vector field X on M , and then indeed h = L X g ∈ D because we trivially have Eh = 0, and Bh = -∇ * ∇X = 0 by the Bochner formula from Step 2.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    If the ALH coordinate system is such that t is a Busemann function, and X is a vector field with L_X g = parallel + ED, then |X| ≤ Ct and |∇_{∂t} X| ≤ C.

    “Claim. Assume our ALH coordinate system is such that t is a Busemann function.If X is a vector field with L X g = parallel + ED, then |X| ≤ Ct and |∇ ∂ t X| ≤ C.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The ALH coordinate system is such that t is a Busemann function.
  • May combine two claims.

    Findingreasoning

    D = Sym^2 R^4 has dimension 10 and hence overcounts the number of moduli of the flat metric g on C^2/Λ by 4; D contains a 4-dimensional space L_lin = {h ∈ D : H(Λ) = 0} of Lie derivatives of g by linear vector fields on C^2/Λ.

    “(i) D has dimension 10 and hence overcounts the number of moduli of the flat metric g on C 2 /Λ by 4. This is because D contains a 4-dimensional space L lin := {h ∈ D : H(Λ) = 0} of Lie derivatives of g by linear vector fields on C 2 /Λ.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    In all the constructed cases, the underlying complex surfaces are complements of fibers in rational elliptic surfaces, and the metrics form one connected moduli space.

    “In all of these cases, the underlying complex surfaces are complements of fibers in rational elliptic surfaces, and so our metrics form one connected moduli space.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation

    A complete Kähler manifold with |Rm| + Σ_{i=1}^{k-1} r^{iλ}|∇^i Scal| ≤ C r^{-2λ} for some k ∈ N and λ ∈ [0,1] is HMG(λ,k,α) for every α ∈ (0,1), and the maps Φ_x can be taken holomorphic.

    “A complete Kähler manifold with |Rm| + k-1 i=1 r iλ |∇ i Scal| ≤ Cr -2λ for some k ∈ N and λ ∈ [0, 1] is HMG(λ, k, α) for every α ∈ (0, 1).Moreover, the maps Φ x : C m ⊃ B → M in Definition 2.6 can be taken to be holomorphic.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [53] Tian, G., 1990, Complete Kähler manifolds with zero Ricci curvature. I, J. Amer. Math. Soc. source
  • May combine two claims.

    Premisecitation

    All finite monodromy types can occur on rational elliptic surfaces, as well as I_b for b∈{1,...,9} and I*_b for b∈{1,...,4}.

    “All finite monodromy types can occur, as well as I b for b ∈ {1, ..., 9} and I * b for b ∈ {1, ..., 4}.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisecitation

    Persson [45] determined all possible configurations of singular fibers on rational elliptic surfaces; there are 279 in total, the generic one being 12×I1.

    “Persson [45] has determined all possible configurations of singular fibers; there are 279 in total, the generic one being 12 × I 1 .”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [45] Miranda, Rick, 1990, Persson’s list of singular fibers for a rational elliptic surface, Math. Z. source
  • The quote only partly states this claim.

    Interpretationreasoning

    The negative dz∧dz components are balanced by adding tf*β with a bump form β ≥ 0 on P1 and t large.

    “We balance these by adding tf * β with a bump form β ≥ 0 on P 1 , t 1.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisenone given

    For a rational elliptic surface X, the natural fibration f: X → P1 is the complete linear system |-K_X|, and for each fiber D=f^{-1}(p) there exists a rational 2-form Ω on X, unique up to scale, such that div(Ω)=-D; all rational 2-forms on X arise this way.

    “Consider a rational elliptic surface X as in Definition 1.1.The natural fibration f : X → P 1 has an intrinsic description as the complete linear system |-K X |, so for each fiber D = f -1 (p) there exists a rational 2-form Ω on X, which is unique up to a scale, such that div(Ω) = -D, and all rational 2-forms on X are obtained in this way.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationreasoning

    The I*b geometry still suffices for Proposition 2.9(ii), but M is then certainly not CYL(γ) for any γ.

    “Notice that this still suffices for Proposition 2.9(ii), but M is then certainly not CYL(γ) for any γ.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    If E=C/Λ is a complex torus and Γ is a finite subgroup of Aut(E), then Γ is generated by a root of unity and is either Z2 (for any Λ), Z4 (for Λ=Z[i]), or Z3, Z6 (for Λ=Z[ζ3]).

    “Let E = C/Λ be a complex torus and let Γ be a finite subgroup of Aut(E), so Γ is generated by a root of unity and either Γ = Z 2 (for any Λ), Γ = Z 4 (for Λ = Z[i]), or Γ = Z 3 , Z 6 (for Λ = Z[ζ 3 ]), ζ m := exp(2πi/m).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisenone given

    The T2-bundles over S1 obtained by restricting U to a loop around 0 are orientable; they are flat (Bieberbach) manifolds if the monodromy is trivial or finite, nilmanifolds for I_b (b≥1), and infranil for I*_b (b≥1).

    “The T 2 -bundles over S 1 obtained by restricting U to a loop around 0 are orientable.They are flat (Bieberbach) manifolds if the monodromy is trivial or finite, nilmanifolds for I b (b ≥ 1), and infranil for I * b (b ≥ 1).”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    A fiber f^{-1}(p) in a general elliptic fibration is reduced if and only if f admits a section near p.

    “A fiber f -1 (p) in a general elliptic fibration is reduced if and only if f admits a section near p.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    In the ALH and Ib cases, derivatives of u decay at the same rate as uū, and in the ALG and I*b cases one gains a factor r^{-1} per derivative, by Proposition 2.9(ii).

    “thus, in the ALH and I b cases, the derivatives of u decay at the same rate as uū, and we even gain a factor of r -1 per derivative in the ALG and I * b cases, by Proposition 2.9(ii).”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    The topological type of a central fiber determines the monodromy, whose order as an element of SL(2,Z) is finite except in the I_b and I*_b cases for b≥1.

    “Here, we only note that the topological type determines the monodromy, whose order as an element of SL(2, Z) is finite except in the I b and I * b cases for b ≥ 1.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    The volume growth is at most 2; as discussed after Proposition 2.4, it was necessary to take care of the integrability condition.

    “The volume growth is at most 2; as discussed after Proposition 2.4, it therefore was indeed necessary to take care of the integrability condition.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationreasoning

    Theorem 1.3 follows from Propositions 3.7 and 2.4, using the SOB properties of ω_sf(α) from Section 3.3.

    “Theorem 1.3 now follows from Propositions 3.7 and 2.4, using the SOB properties of ω sf (α) from Section 3.3.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationreasoning

    The asymptotic cones of the complete Ib and I*b metrics are R+ and R2/Z2, respectively, as for the complete I0 and I*0 metrics.

    “so in particular the asymptotic cones are R + , R 2 /Z 2 , as for the complete I 0 , I * 0 metrics”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    M satisfies CYL(1/3) according to Definition 2.5, as well as the diameter growth condition from Definition 2.8.

    “Taken together, these properties already imply that M satisfies CYL( 13 ) according to Definition 2.5, as well as the diameter growth condition from Definition 2.8.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationreasoning

    In the setting of Theorem 1.3, besides deforming S^1 and T^2 separately, there are 2 more moduli to break the S^1 × T^2 splitting, and these can be realized inside every fixed Kähler class with respect to the given complex structure.

    “Thus, in the setting of Theorem 1.3, besides deforming the S 1 and T 2 separately, we have 2 more moduli to break the S 1 × T 2 splitting.In fact, these can be realized inside every fixed Kähler class with respect to the given complex structure.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisenone given

    The metric g on the base has positive injectivity radius, while the fibers are almost totally geodesic flat tori of constant area whose shortest closed geodesic is given by the monodromy invariant generator τ1.

    “The point here is that the metric g on the base has positive injectivity radius, while the fibers are almost totally geodesic flat tori of constant area whose shortest closed geodesic is given by the monodromy invariant generator τ 1 .”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation

    Example 3.1 explains why the complete cone angle when removing one fiber equals the incomplete cone angle when removing its dual.

    “Example 3.1 also explains why the complete cone angle when removing one fiber is equal to the incomplete cone angle when removing its dual.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Example 3.1

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning

    The calculation of |Θ(x)|^2 was performed on a computer, proceeding from (3.16).

    “This was calculated on a computer, proceeding from (3.16).”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim.

    Interpretationreasoning

    Proposition 3.7 follows immediately from what is established in Claim 4.

    “Proposition 3.7 follows immediately from what is established in Claim 4.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Interpretationreasoning

    The asymptotics in Theorem 1.5 follow from Proposition 2.9.

    “The asymptotics in Theorem 1.5 follow from Proposition 2.9.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given

    All finite monodromies can be treated in this way and lead to semi-flat metrics with similar properties.

    “All finite monodromies can be treated in this way, and lead to semi-flat metrics with similar properties.”
    Quote in the paperNot a substantial claim
92 of 92
  • The paper relies on this without support.

    For a rational elliptic surface X, f = |-K_X|, and for each fiber D = f^{-1}(p) there exists precisely one rational 2-form Ω up to scale with div(Ω) = -D, and all rational 2-forms on X arise in this way.

    “In fact, f = |-K X |, so for each fiber D = f -1 (p), to be understood as a divisor, there exists precisely one rational 2-form Ω (up to a scale) with div(Ω) = -D, and all rational 2-forms on X arise in this way.”
  • The paper relies on this without support.

    Yau's method for solving the Monge-Ampère equation produces bounded solutions by default.

    “Yau's method for solving the Monge-Ampère equation produces bounded solutions by default.”
  • The authors state this as an assumption.

    In Section 3.3, D does not contain (-1)-curves and is reduced, equivalently f admits a holomorphic section, equivalently U|Δ*≅(Δ*×C)/(Zτ1+Zτ2).

    “Assume that D does not contain (-1)-curves and is reduced or equivalently that f admits a holomorphic section, or yet equivalently U | Δ * ∼ = (Δ * × C)/(Zτ 1 + Zτ 2 ) for some multivalued holomorphic functions τ 1 , τ 2 : Δ * → C.”
  • The authors state this as an assumption.

    In Section 3.3, div(Ω) is either -D (the interesting case on a rational elliptic surface) or 0 (the Gross-Wilson setting).

    “In this section, we either assume div(Ω) = -D, which is the interesting case on a rational elliptic surface, or div(Ω) = 0, corresponding to the Gross-Wilson setting.”
  • The authors state this as an assumption.

    In the barrier method illustration, β>2 is an integer and (M,ω0) is asymptotically a bundle with bounded fibers over a β-dimensional cone with radius function r.

    “To illustrate the barrier method, suppose that β > 2 is an integer and (M, ω 0 ) is asymptotically a bundle with bounded fibers over a β-dimensional cone with radius function r.”
  • The authors state this as an assumption.

    In the hyper-Kähler setting, X admits a holomorphic symplectic form Υ such that all fibers X_s are complex Lagrangians.

    “Let dim S = m and assume that X admits a holomorphic symplectic form Υ such that all X s are complex Lagrangians.”
  • The authors state this as an assumption.

    In the Calabi-Yau setting, dim S=1 and X admits a holomorphic volume form Ω.

    “Calabi-Yau setting.Let dim S = 1 and suppose that X admits a holomorphic volume form Ω.”
  • The authors state this as an assumption.

    For the type II finite monodromy analysis, J(0)=0 and mult_0 J=m∈N.

    “Let J (0) = 0, mult 0 J = m ∈ N.”
  • The authors state this as an assumption.

    In the finite monodromy cases, the monodromy matrix A is of finite order.

    “The calculations for all types of singular fibers where A is of finite order are fairly similar”
  • The authors state this as an assumption.

    (U,g_sf,ε) is imbedded into a complete Riemannian manifold M as the only end of M.

    “Finally, we assume for convenience that (U, g sf,ε ) is imbedded into a complete Riemannian manifold M as the only end of M ; fixing a base point x 0 ∈ U , we then let r x := dist M (x 0 , x).”
  • The paper relies on this without support.

    There is a disk Δ = {|z| < 1} in P1 with z(p)=0 such that all fibers of f over Δ* are smooth.

    “Fix a disk Δ = {|z| < 1} ⊂ P 1 with z(p) = 0 such that all fibers of f over Δ * are smooth, and write X| Δ * = (Δ * × C)/(Zτ 1 + Zτ 2 ) with τ 1 , τ 2 from Table 1.”
  • The authors state this as an assumption.

    For all bad cycles C, ω, C = 0.

    “ω, C = 0 (by assumption)”
  • The authors state this as an assumption.

    ∫ ω^2 < ∞.

    “ω 2 < ∞ by assumption”
  • The paper relies on this without support.

    Ω = z^{-(N+1)} k(z) dz ∧ dw with k(0)=0.

    “Note that if Ω = z -(N +1) k(z)dz ∧ dw with k(0) = 0 as usual, then”
  • The authors state this as an assumption.

    The ALH coordinate system is such that t is a Busemann function.

    “Assume our ALH coordinate system is such that t is a Busemann function.”
  • The authors state this as an assumption.

    The cross section T^3 = S^1 × T^2 is an isometric product.

    “Suppose the cross section T 3 = S 1 × T 2 is an isometric product.”
  • The paper relies on this without support.

    ALH spaces can be glued by their ends to construct hyper-Kähler metrics on K3.

    “A folklore result says that ALH spaces can be glued by their ends to construct hyper-Kähler metrics on K3; an analogous problem for G 2 -manifolds was solved in [34].”
17 of 17

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Example 2.10 gives the opposite exponential rate

    Minor

    The stated bound exp(-δr^{-2/3}) tends to 1 rather than decaying as r grows. The proof of Theorem 1.5 gives exp(-δr^{2/3}) for the same I_b case.

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 2

  1. Hein, Hans-Joachim, 2010, On gravitational instantons
  2. Huybrechts, Daniel, 2005, Complex geometry

Cited by

Sorted by citations

Authors
Hein, H.-J.
Affiliations
Imperial College London (GB)
Corresponding author
Hein, Hans-Joachim
Venue
Journal of the American Mathematical Society
Published
2011-11-18
Volume
25
Issue
2
Pages
355-393
ISSN
  • 0894-0347 (ISSN-L)
  • 1088-6834
OpenAlex
W2161407970
Cited by
87
References
48
Citations by year
2026: 1 · 2025: 3 · 2024: 29 · 2023: 5 · 2022: 4 · 2021: 11 · 2020: 8 · 2019: 8 · 2018: 3 · 2017: 6 · 2016: 1 · 2015: 3 · 2014: 1 · 2013: 4
FWCI
2.02
Type
journal article
Language
en
Open access
Locations
Journal of the American Mathematical Society (publishedVersion, public-domain)
Funders
Peking University
Topics
  • Physical Sciences › Mathematics › Geometry and Topology › Geometry and complex manifolds
  • Physical Sciences › Mathematics › Geometry and Topology › Algebraic Geometry and Number Theory
  • Physical Sciences › Mathematics › Applied Mathematics › Geometric Analysis and Curvature Flows
Keywords
gravitational instantons, Ricci-flat Kähler metrics, rational elliptic surfaces, elliptic fibrations, complete metrics, singular fibers, volume growth, monodromy

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