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A volume comparison theorem for characteristic numbers

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Abstract

We show that assuming lower bounds on the Ricci curvature and the injectivity radius the absolute value of certain characteristic numbers of a Riemannian manifold, including all Pontryagin and Chern numbers, is bounded proportionally to the volume. The proof relies on Chern–Weil theory applied to a connection constructed from Euclidean connections on charts in which the metric tensor is harmonic and has bounded Hölder norm. We generalize this theorem to a Gromov–Hausdorff closed class of rough Riemannian manifolds defined in terms of Hölder regularity. Assuming an additional upper Ricci curvature bound, we show that also the Euler characteristic is bounded proportionally to the volume. Additionally, we remark on a volume comparison theorem for Betti numbers of manifolds with an additional upper bound on sectional curvature. It is a consequence of a result by Bowen.

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Acknowledgements

The author thanks his PhD supervisor Prof. Dr. Thomas Schick for his guidance and support during the author’s PhD project from which this paper developed.

Funding

The author was supported by the DFG Research Training Group 1493 Mathematische Strukturen in der modernen Quantenphysik and the ISF project Action now: geometry and dynamics of group actions.

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Correspondence to Daniel Luckhardt.

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Coordinate independence

Coordinate independence

We check that the curvature defined in the notation of Sect. 4 by 4.5 which can be stated as

$$\begin{aligned} {}^\varphi \,{\text{R}}^{k}_{\lambda \mu \nu } = \sum _{i\in I} \lambda _{i} \sum _{l} \left( \left( x^{i}_{k, l} \circ y^{i} \right) _{,\mu } y^{i}_{l, \nu \lambda }\right) _{[\mu \nu ]} + \left( \lambda _{i, \mu } {}^i\,{\Gamma }_{\nu \lambda }^{k}\right) _{[\mu \nu ]} + \sum _{\kappa } \left( {}^\varphi \,{\Gamma }^{k}_{\mu \kappa }{}^\varphi \,{\Gamma }^\kappa _{\nu \lambda }\right) _{[\mu \nu ]} \end{aligned}$$
(A.1)

is actually coordinate independent. The standard textbook calculation could be referred to if a third derivative of transition maps would exists.

Lemma A.1

Let M be a manifold, \( \varphi _{i}:U_{i} \rightarrow M \) be charts in a \({{\mathrm{C}}^{2}}\)-atlas of M, and \( \lambda _{i} \) be a corresponding \({{\mathrm{C}}^{1}}\)-partition of unity. For any two charts \( \varphi :U \rightarrow M \) and \( \varphi ' :U'\rightarrow M \) the expression defined by (4.5) coincide on \( \varphi (U) \cap \varphi '(U') \) as (3,1)-tensor, i.e.

$$\begin{aligned} \sum _{\lambda ', \mu ', \nu ', k'} \left( {}^{\varphi ^{\prime }}\,{R}^{k'}_{\lambda '\mu '\nu '} \circ x'\right) x'_{\lambda ', \lambda } x'_{\mu ', \mu } x'_{\nu ', \nu } \left( x_{k, k'} \circ x'\right) = {}^\varphi\, {\text{R}}^{k}_{\lambda \mu \nu }. \end{aligned}$$

Proof

We repeat all crucial definitions in the primed and non-primed versions

$$\begin{aligned} x= \varphi^{-1} \circ \varphi ',x'= \varphi '^{-1} \circ \varphi ,\\ x^{i}= \varphi ^{-1} \circ \varphi _{i},x'^{i}= \varphi '^{-1} \circ \varphi _{i},\\ y^{i}= \varphi _{i}^{-1} \circ \varphi ,y^{\prime i}= \varphi _{i}^{-1} \circ \varphi ', \\ {}^i{\varGamma }_{\mu \nu }^{k}= \sum _{l} \left( x^{i}_{k,l} \circ y^{i}\right) \left( y^{i}_{l,\mu \nu }\right) ,{}^i{\varGamma }_{\mu \nu }^{\prime k}= \sum _{l} \left( x^{\prime i}_{k,l} \circ y^{\prime i}\right) \left( y^{\prime i}_{l,\mu \nu }\right) ,\\ {}^\varphi {\varGamma }_{\mu \nu }^{k}= \sum _{i\in I} \lambda _i\,{}^i{\varGamma }_{\mu \nu }^{k},{}^{\varphi '}{\varGamma }_{\mu \nu }^{k}= \sum _{i\in I} \lambda _{i} {}^i{\varGamma }_{\mu \nu }^{\prime k}. \end{aligned}$$

defined on the suitable domains and the abuse of notation \(\lambda _{i} = \lambda _{i} \circ \varphi \). Additionally, we introduce the shorthand

$$\begin{aligned} (h_{\mu \mu '\nu \nu '})_{[\mu \nu ]'} :=h_{\mu \mu '\nu \nu '} - h_{\nu \nu '\mu \mu '} . \end{aligned}$$

Observe that in case \( h_{\mu \mu '\nu \nu '} = f_{\mu \mu '} \cdot g_{\nu \nu '} \)

$$\begin{aligned} \nonumber \sum \limits _{\mu '\nu '} \left( h_{\mu '\mu '\nu '\nu '}\right) _{[\mu \nu ]'}&= \left( \sum \limits _{\mu '} f_{\mu \mu '} \right) \left( \sum \limits _{\nu '} g_{\nu \nu '} \right) - \left( \sum \limits _{\nu '} f_{\nu \nu '} \right) \left( \sum \limits _{\mu '} g_{\mu \mu '} \right) \\&= \left( \sum \limits _{\mu '} f_{\mu \mu '} \sum \limits _{\nu '} g_{\nu \nu '} \right) _{[\mu \nu ]}. \end{aligned}$$
(A.2)

We have \( x' :=\varphi '^{-1} \circ \varphi = x'^{i} \circ y^{i} \) and \( x :=\varphi ^{-1} \circ \varphi ' = x^{i} \circ y'^{i} \) where defined. Observe that for the differential \( D\,{ id }:{\mathbb{R}}^{d} \rightarrow {\mathbb{R}}^{d} \) of the identity the following identity holds

$$\begin{aligned} 0&= (D\,{ id })_{,\lambda } = ({\text{D}}\, x\circ x' )_{,\lambda } = \left( \left( \sum \limits _{l} x_{k,l} \circ x' \cdot x'_{l,\nu } \right) _{k\nu } \right) _{,\lambda } \nonumber \\&= \sum \limits _{l} \left( (x_{k,l} \circ x')_{,\lambda } x'_{l,\nu } + (x_{k,l} \circ x') x'_{l,\nu \lambda } \right) _{k\nu }. \end{aligned}$$
(A.3)

Finally, we prove the lemma. Fix any \( \lambda , \mu , \nu , k \in \{1,\ldots , d\} \) and observe

$$\begin{aligned} \sum _{\lambda ', \mu ', \nu ', k'} \big ({}^{\varphi ^{\prime }}\,{R}^{k'}_{\lambda '\mu '\nu '} {}\circ x'\big ) x'_{\lambda ', \lambda } x'_{\mu ', \mu } x'_{\nu ', \nu } \big (x_{k, k'} \circ x'\big ) \end{aligned}$$

plug in definition (A.1) for \( {}^{\varphi ^{\prime }}\,{R}^{k'}_{\lambda '\mu '\nu '} \) and use the abuse of notation \(\lambda _{i, \mu '} = (\lambda _{i} \circ \varphi ')_{,\mu } \)

$$\begin{aligned}&= \sum _{i\in I} \lambda _{i} \sum _{\lambda ', k', l'} \sum _{\mu ', \nu '} \left( \left( \left( x^{\prime i}_{k', l'} \circ y^{\prime i} \right) _{,\mu '} \circ x'\right) x'_{\mu ', \mu } \left( y^{\prime i}_{l', \nu '\lambda '} \circ x'\right) x'_{\lambda ', \lambda } x'_{\nu ', \nu } \left( x_{k, k'} \circ x'\right) \right) _{[\mu \nu ]'}\\&\quad + \sum _{ i\in I } \sum _{\lambda ', k'} \sum _{\mu ', \nu '} \left( \lambda _{i, \mu '} x'_{\mu ', \mu } \left( {}^{i}\Gamma_{\nu ' \lambda '}' \circ x'\right) ^{k'} x'_{\lambda ', \lambda } x'_{\nu ', \nu } \left( x_{k, k'} \circ x'\right) \right) _{[\mu \nu ]'}\\&\quad + \sum _{\lambda ', k', \kappa '} \sum _{\mu ', \nu '} \left( {}^{\varphi'} \Gamma^{k'}_{\mu '\kappa '} {}^{\varphi '}\Gamma^{\kappa '}_{\nu '\lambda '} x'_{\lambda ', \lambda } x'_{\mu ', \mu } x'_{\nu ', \nu } \left( x_{k, k'} \circ x'\right) \right) _{[\mu \nu ]'} \end{aligned}$$

apply formula (A.2) to each summand \(\sum _{\mu ', \nu '}(\ldots )_{[\mu \nu ]'}\)

$$\begin{aligned}&= \sum _{ i\in I } \sum _{\lambda ', k', l'} \lambda _{i} \Bigl ( \textstyle \overbrace{\textstyle \sum \limits _{\mu '} \big (\big (x^{\prime i}_{k', l'} \circ y^{\prime i} \big )_{,\mu '} \circ x'\big ) x'_{\mu ', \mu } }^{\text {change of variables}} \cdot \sum \limits _{\nu '} \underbrace{ \big (y^{\prime i}_{l', \nu '\lambda '} \circ x'\big ) x'_{\lambda ', \lambda } }_{\text {change of variables}} x'_{\nu ', \nu } \big (x_{k, k'} \circ x'\big ) \Bigr )_{[\mu \nu ]}\\&\quad + \sum _{ i\in I } \sum_{\lambda ', k'} \Bigl ( \underbrace{\textstyle \sum _{\mu '} \lambda _{i, \mu '} x'_{\mu ', \mu } }_{\text {change of variables}} \underbrace{\textstyle \sum _{\nu '} \big ({}^i\,{\Gamma }_{\nu ' \lambda '}' \circ x'\big )^{k'} x'_{\lambda ', \lambda } x'_{\nu ', \nu } \big (x_{k, k'} \circ x'\big ) }_{\text {apply formula}\, (4.1)} \Bigr )_{[\mu \nu ]} \\&\quad + \sum _{\lambda ', k', \kappa '} \left( \textstyle \sum \limits _{\mu '} {}^{\varphi '}\,{\Gamma }^{k'}_{\mu '\kappa '} x'_{\mu ', \mu } \big (x_{k, k'} \circ x'\big ) \sum \limits _{\nu '} {}^{\varphi '}\,{\Gamma }^{\kappa '}_{\nu '\lambda '} x'_{\lambda ', \lambda } x'_{\nu ', \nu } \right) _{[\mu \nu ]} \\&= \sum _{ i\in I } \sum _{k', l'} \lambda _{i} \Bigl (\textstyle \big ( \underbrace{x^{\prime i}_{k', l'}}_{=\big (x'\circ x^{i}\big )_{k',l'} } {}\circ {} \underbrace{y^{\prime i} \circ x'}_{= y^{i}} \Big )_{,\mu } \sum _{\nu '} \Big ( \underbrace{y^{\prime i}_{l', \nu '} }_{=(y^{i} \circ x)_{l',\nu '}} {}\circ x' \Big )_{, \lambda } x'_{\nu ', \nu } \big (x_{k, k'} \circ x'\big ) \Bigr )_{[\mu \nu ]} \\&\quad + \sum _{i\in I} \left( \ \lambda _{i, \mu } \left( {}^i\,{\Gamma }_{\nu \lambda }^{k} - \sum _{l} \big (x_{k,l} \circ x'\big ) \big (x'_{l,\nu \lambda }\big ) \right) \right) _{[\mu \nu ]} \\&\quad + \sum _{\lambda ', k', \kappa ', \mu ', \nu ', m} \Bigl ( {}^{\varphi '}\,{\Gamma }^{k'}_{\mu 'm} x'_{\mu ', \mu } (x_{k, k'} \circ x') \cdot \underbrace{ \delta _{m\kappa '} }_{ (*)} \cdot {}^{\varphi '}\,{\Gamma }^{\kappa '}_{\nu '\lambda '} x'_{\lambda ', \lambda } x'_{\nu ', \nu } \Bigr )_{[\mu \nu ]} \end{aligned}$$

\((*)\): \( \delta _{m\kappa '} = \delta _{m\kappa '} \circ x'\) = \((D \,{ id } )_{m\kappa '} \circ x' = (D (x'\circ x))_{m\kappa '} \circ x'\) = \( (\sum\nolimits_{ \kappa } x'_{m, \kappa } \circ x \cdot x_{\kappa , \kappa '} ) \circ x'\) = \( \sum\nolimits_\kappa x'_{m, \kappa } (x_{\kappa , \kappa '} \circ x')\)

$$\begin{aligned}&=\sum _{\begin{array}{c} i\in I \\ k', l' \end{array}} \lambda _{i} \left( \begin{aligned}&\textstyle \bigl (\bigl ( \sum _\kappa x'_{k', \kappa } \circ x^{i} \cdot x^{i}_{\kappa ,l'} \bigr ) \circ y^{i} \bigr ){}_{,\mu } \\&\textstyle \cdot \sum _{\nu '} \bigl (\bigl ( \sum _{l} y^{i}_{l', l}\circ x \cdot x_{l, \nu '}\bigr ) \circ x'\bigr ){}_{, \lambda } \textstyle \cdot x'_{\nu ', \nu } (x_{k, k'} \circ x') \end{aligned} \right) _{[\mu \nu ]} \\&\quad + \sum _{i\in I} \bigl ( \lambda _{i, \mu } {}^i\,{\Gamma }_{\nu \lambda }^{k} \bigr )_{[\mu \nu ]} - \sum _{l} \left( \left( \sum _{i\in I} \lambda _{i}\right) _{, \mu } \big (x_{k,l} \circ x'\big ) \big (x'_{l,\nu \lambda }\big ) \right) _{[\mu \nu ]} \\&\quad + \sum _\kappa \Biggl ( \underbrace{\textstyle \sum \limits _{k', \mu ', m} {}^{\varphi '}\,{\Gamma }^{k'}_{\mu 'm} x'_{\mu ', \mu } \big (x_{k, k'} \circ x'\big ) x'_{m, \kappa } }_{\text{apply formula }\, (4.1)} \underbrace{\textstyle \sum \limits _{\lambda ', \kappa ', \nu '} {}^{\varphi '}\,{\Gamma }^{\kappa '}_{\nu '\lambda '} x'_{\lambda ', \lambda } x'_{\nu ', \nu } (x_{\kappa , \kappa '} \circ x') }_{\text{apply formula }\, (4.1)} \Biggr )_{[\mu \nu ]} \\&= \sum _{\begin{array}{c} i\in I \\ k', l' \end{array}} \lambda _{i} \left( \sum _{\kappa } \big ( x'_{k', \kappa } \cdot x^{i}_{\kappa ,l'} \circ y^{i} \big )_{,\mu } \sum _{\nu , l} \big ( y^{i}_{l', l} \cdot x_{l, \nu '} \circ x'\big )_{, \lambda } x'_{\nu ', \nu } (x_{k, k'} \circ x') \right) _{[\mu \nu ]} \\& \quad + \smash {\overbrace{\sum _{i\in I} \bigl ( \lambda _{i, \mu } {}^i\,{\Gamma }_{\nu \lambda }^{k}\bigr )_{[\mu \nu ]}}^{=:M}} - \sum _{l} \Bigl ( \smash {\overbrace{1_{, \mu } }^{=0}} (x_{k,l} \circ x') x'_{l,\nu \lambda } \Bigr )_{[\mu \nu ]} \\& \quad + \sum _{ \kappa } \left( \left( {}^{\varphi} \,{\Gamma }^{k}_{\mu \kappa } - \sum _{l} \big (x_{k,l} \circ x'\big ) x'_{l,\mu \kappa } \right) \left({}^ \varphi \,{\Gamma }^\kappa _{\nu \lambda } - \sum _{l} \big (x_{\kappa ,l} \circ x'\big ) x'_{l, \nu \lambda } \right) \right) _{[\mu \nu ]} \end{aligned}$$
$$\begin{aligned}&= \sum _{\begin{array}{c} i\in I \\ k', l' \end{array}} \lambda _{i} \left( \textstyle \begin{aligned}&\textstyle \sum _{\kappa } \bigl ( x'_{k', \kappa \mu } \big (x^{i}_{\kappa ,l'} \circ y^{i}\big ) + x'_{k', \kappa } \big (x^{i}_{\kappa ,l'} \circ y^{i}\big )_{,\mu } \bigr ) \\&\textstyle \cdot \sum _{\nu ', l} \bigl ( y^{i}_{l', l\lambda } \big (x_{l, \nu '} \circ x'\big ) + y^{i}_{l', l } \big (x_{l, \nu '} \circ x'\big )_{, \lambda } \bigr ) x'_{\nu ', \nu } \big (x_{k, k'} \circ x'\big ) \end{aligned} \right) _{[\mu \nu ]} \\& \quad + M + \sum _{\kappa } \textstyle \begin{aligned}&\textstyle \Big ( {}^\varphi\, {\Gamma }^{k}_{\mu \kappa } {}^\varphi\, {\Gamma }^\kappa _{\nu \lambda } + \sum _{l, l'} {}^\varphi \,{\Gamma }^{k}_{\mu \kappa } \big (x_{\kappa ,l} \circ x'\big ) x'_{l, \nu \lambda } \\&\textstyle - {}^\varphi \,{\Gamma }^\kappa _{\nu \lambda } \big (x_{k,l} \circ x'\big ) x'_{l,\mu \kappa } + \big (x_{k,l} \circ x'\big ) x'_{l,\mu \kappa } \smash {\underbrace{\big (x_{\kappa ,l'} \circ x'\big ) x'_{l', \nu \lambda }}_{ \text{use formula }\, (A.3) }} \Big )_{[\mu \nu ]} \end{aligned} \\&= \sum _{\begin{array}{c} i\in I \\ l, \kappa \end{array}} \lambda _{i} \left( \textstyle \begin{aligned}&\textstyle \sum _{k', l'} \bigl ( x'_{k', \kappa \mu } (x^{i}_{\kappa ,l'} \circ y^{i}) + x'_{k', \kappa } \big (x^{i}_{\kappa ,l'} \circ y^{i}\big )_{,\mu } \bigr ) \\&\textstyle \cdot \sum _{\nu } \bigl ( y^{i}_{l', l\lambda } \big (x_{l, \nu '} \circ x'\big ) + y^{i}_{l', l } \big (x_{l, \nu '} \circ x'\big )_{, \lambda } \bigr ) x'_{\nu ', \nu } \big (x_{k, k'} \circ x'\big ) \end{aligned} \right) _{[\mu \nu ]} \\& \quad + \underbrace{ \begin{aligned}&{\textstyle M + \sum _{\kappa } {}^\varphi \,{\Gamma }^{k}_{\mu \kappa } {}^\varphi \,{\Gamma }^\kappa _{\nu \lambda } -\sum _{\kappa , l, l'} {}^\varphi \,{\Gamma }^{k}_{\mu \kappa } \big (x_{\kappa ,l} \circ x'\big ) x'_{l, \nu \lambda } } \\&+ {}^\varphi \,{\Gamma }^\kappa _{\nu \lambda } (x_{k,l} \circ x') x'_{l,\mu \kappa } + (x_{k,l} \circ x') x'_{l,\mu \kappa } (x_{\kappa ,l'} \circ x')_{,\lambda } x'_{l', \nu } \end{aligned} }_{=:T } \end{aligned}$$
$$\begin{aligned}&= \sum _{\begin{array}{c} i\in I,\\ l, \kappa \end{array}} \lambda _{i} \left( \begin{aligned}&\textstyle \sum \limits _{k'} x'_{k', \kappa \mu } \big (x_{k, k'} \circ x'\big ) \sum \limits _{l'} \big (x^{i}_{\kappa ,l'} \circ y^{i}\big ) y^{i}_{l', l\lambda } \sum \limits _{\nu '} \big (x_{l, \nu '} \circ x'\big ) x'_{\nu ', \nu } \\&+ \textstyle \sum \limits _{l'} \big (x^{i}_{\kappa ,l'} \circ y^{i}\big )_{,\mu }y^{i}_{l', l\lambda } \sum \limits _{k'} x'_{k', \kappa } \big (x_{k, k'} \circ x'\big ) \sum \limits _{\nu '} \big (x_{l, \nu '} \circ x'\big ) x'_{\nu ', \nu } \\&\textstyle + \sum \limits _{k', \nu '} x'_{k', \kappa \mu } \big (x_{l, \nu '} \circ x'\big )_{, \lambda } x'_{\nu ', \nu } \big (x_{k, k'} \circ x'\big ) \sum \limits _{l'} \big (x^{i}_{\kappa ,l'} \circ y^{i}\big ) y^{i}_{l', l } \\&\textstyle + \sum \limits _{l',\nu '} \smash {\underbrace{\big (x^{i}_{\kappa ,l'} \circ y^{i}\big )_{,\mu } y^{i}_{l', l }}_{ \text{use formula}\, (A.3)}} \smash {\underbrace{(x_{l, \nu '} \circ x')_{, \lambda } x'_{\nu ', \nu }}_{ \text{use formula }\, (A.3)} \sum \limits _{k'} (x_{k, k'} \circ x') x'_{k', \kappa }} \end{aligned} \right) _{[\mu \nu ]} + T\\&= \sum _{\begin{array}{c} i\in I \\ l, \kappa \end{array}} \lambda _{i} \left( \textstyle \begin{aligned}&\textstyle \sum _{k'} x'_{k', \kappa \mu } \big (x_{k, k'} \circ x'\big ) {}^i\,\Gamma ^\kappa _{l\lambda } \delta _{l\nu } \textstyle + \sum _{l'} \big (x^{i}_{\kappa ,l'} \circ y^{i}\big )_{,\mu }y^{i}_{l', l\lambda } \delta _{\kappa k} \delta _{l\nu } \\&\textstyle + \sum _{k', \nu '} x'_{k', \kappa \mu } \big (x_{l, \nu '} \circ x'\big )_{, \lambda } x'_{\nu ', \nu } \big (x_{k, k'} \circ x'\big ) \delta _{\kappa l} \\&\textstyle + \sum _{l',\nu '} \big (x^{i}_{\kappa ,l'} \circ y^{i}\big ) y^{i}_{l', l \mu } \big (x_{l, \nu '} \circ x'\big ) x'_{\nu ', \nu \lambda } \delta _{k \kappa } \end{aligned} \right) _{[\mu \nu ]} + T \\&= \sum _{\begin{array}{c} i\in I \\ l, \kappa \end{array}} \lambda _{i} \left( \textstyle \begin{aligned}&\textstyle \sum _{k'} x'_{k', \kappa \mu } \big (x_{k, k'} \circ x'\big ) {}^i\,\Gamma ^\kappa _{\nu \lambda } \textstyle + \sum _{l'} \big (x^{i}_{k ,l'} \circ y^{i}\big )_{,\mu }y^{i}_{l', \nu \lambda } \\&\textstyle + \sum _{k', \nu '} x'_{k', \kappa \mu } \big (x_{\kappa , \nu '} \circ x'\big )_{, \lambda } x'_{\nu ', \nu } \big (x_{k, k'} \circ x'\big ) \\&\textstyle + \sum _{\nu '} {}^i\,\Gamma ^{k}_{\mu l} \big (x_{l, \nu '} \circ x'\big ) x'_{\nu ', \nu \lambda } \end{aligned} \right) _{[\mu \nu ]} + T\end{aligned}$$
$$\begin{aligned}& =\sum _{i\in I} \lambda _{i}\sum _{l, \kappa } \left( \textstyle \begin{aligned}&\textstyle \sum \limits _{k'} x'_{k', \kappa \mu } \big (x_{k, k'} \circ x'\big ) {}^\varphi \,\Gamma ^\kappa _{\nu \lambda } \textstyle + \sum \limits _{l'} \big (x^{i}_{k ,l'} \circ y^{i}\big )_{,\mu }y^{i}_{l', \nu \lambda } \\&\textstyle + \sum \limits _{k', \nu '} x'_{k', \kappa \mu } \big (x_{\kappa , \nu '} \circ x'\big )_{, \lambda } x'_{\nu ', \nu } \big (x_{k, k'} \circ x'\big ) + \sum \limits _{\nu '} {}^\varphi\, \Gamma ^{k}_{\mu l} \big (x_{l, \nu '} \circ x'\big ) x'_{\nu ', \nu \lambda } \end{aligned} \right) _{[\mu \nu ]} \\&+ \sum _{i\in I} \bigl ( \lambda _{i, \mu }{}^ i\,{\Gamma }_{\nu \lambda }^{k} \bigr )_{[\mu \nu ]} + \sum _{\kappa } {}^\varphi \,{\Gamma }^{k}_{\mu \kappa } {}^\varphi \,{\Gamma }^\kappa _{\nu \lambda } \\&- \sum _{\kappa , l, l'} {}^\varphi \,{\Gamma }^{k}_{\mu \kappa } \big (x_{\kappa ,l} \circ x'\big ) x'_{l, \nu \lambda } + {}^\varphi \,{\Gamma }^\kappa _{\nu \lambda } \big (x_{k,l} \circ x'\big ) x'_{l,\mu \kappa } + \big (x_{k,l} \circ x'\big ) x'_{l,\mu \kappa } \big (x_{\kappa ,l'} \circ x'\big )_{,\lambda } x'_{l', \nu } \\&= \sum _{i\in I} \lambda _{i} \sum _{l'} \bigl ( \big (x^{i}_{k ,l'} \circ y^{i}\big )_{,\mu }y^{i}_{l', \nu \lambda } \bigr )_{[\mu \nu ]} + \bigl (\lambda _{i, \mu }{}^ i\,{\Gamma }_{\nu \lambda }^{k}\bigr )_{[\mu \nu ]} + \sum _{ \kappa } \bigl ({}^\varphi \,{\Gamma }^{k}_{\mu \kappa } {}^\varphi \,{\Gamma }^\kappa _{\nu \lambda }\bigr )_{[\mu \nu ]} \\&= {}^\varphi \,{\text{R}}^{k}_{\lambda \mu \nu }. \end{aligned}$$

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Luckhardt, D. A volume comparison theorem for characteristic numbers. Ann Glob Anal Geom 60, 687–708 (2021). https://doi.org/10.1007/s10455-021-09774-5

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