25 February 2026 16 min read
For the Poincaré half-space model in dimension 2, the metric evaluates on the coordinate tangent vectors \(\frac{\partial}{\partial x}, \frac{\partial}{\partial y} \in T_pM\) as \[g_p\!\left(\frac{\partial}{\partial x^i}\bigg|_p,\;\frac{\partial}{\partial x^j}\bigg|_p\right) = \frac{1}{y^2}\,\delta_{ij},\] i.e. the coordinate tangent vectors are orthogonal and each has length \(\frac{1}{y}\) — shrinking to zero as \(p\) approaches the boundary \(y\to 0\), which is what makes the space “infinitely large” near the boundary.。关于这个话题，体育直播提供了深入分析
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Американскому сенатору стало «страшнее, чем когда либо» после брифинга по Ирану02:37，这一点在体育直播中也有详细论述
南方周末：2025年法院签发家庭教育指导令的数量和执行情况如何？
Apple has also bumped up the RAM from 8GB from the last-gen model to 12GB. Given the sharp increase in RAM prices in recent months, it’s slightly surprising that Apple is sticking to the same prices for the iPad Air. The 11-inch M4 iPad Air starts at $599 while the 13-inch version starts at $799, each with 128GB of storage. There's a $50 discount for those buying it for educational use.