ScalingStacks

Definition 1.1 . [02YV]

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Definition 1.1.

Let BB be an nn-dimensional manifold. An affine structure on BB is given by an atlas {(Ui,ψi)}\{(U_{i},\psi_{i})\} of coordinate charts ψi:Ui→ℝn\psi_{i}:U_{i}\rightarrow\mathbb{R}^{n}, whose transition functions ψi∘ψj−1\psi_{i}\circ\psi_{j}^{-1} lie in Aff⁡(ℝn){\rm Aff}(\mathbb{R}^{n}). We say the affine structure is tropical if the transition functions lie in ℝn⋊G​L​(ℤn)\mathbb{R}^{n}\rtimes GL(\mathbb{Z}^{n}), i.e., have integral linear part. We say the affine structure is integral if the transition functions lie in Aff⁡(ℤn){\rm Aff}(\mathbb{Z}^{n}).

If an affine manifold BB carries a Riemannian metric gg, then we say the metric is affine Kähler or Hessian if gg is locally given by gi​j=∂2K/∂yi​∂yjg_{ij}=\partial^{2}K/\partial y_{i}\partial y_{j} for some convex function KK and y1,…,yny_{1},\ldots,y_{n} affine coordinates.

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