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  1. Identity Transformation

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    Identity in Transformation Groups
    In the context of transformation groups, such as the General Linear Group ($\mathrm{GL}(n, \mathbb{R})$) or the Lorentz Group, the identity transformation is the null operation. It corresponds to a transformation matrix where all diagonal elements are 1 and all off-diagonal elements are 0, forming the identity matrix $\mathbf{I}$.
    For a Lorentz transformation $\Lambda$…
  2. Levi Civita Connection

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    The Trivial Case of Euclidean Space
    In Euclidean space ($\mathbb{R}^n$) endowed with the standard flat metric (the identity matrix $I$), the Christoffel symbols $\Gamma^{\rho}{}_{\mu\nu}$ all vanish. This is because the partial derivatives of the constant metric components are zero. Thus, in flat Euclidean space, the Levi-Civita connection reduces precisely to the ordinary [partial deriva…
  3. U(1) Symmetry Group

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    The Lie algebra associated with $\mathrm{U}(1)$, denoted $\mathfrak{u}(1)$, is one-dimensional and is spanned by the generator $T$ corresponding to infinitesimal transformations:
    $$U(\epsilon) = e^{i\epsilon T} \approx 1 + i\epsilon T$$
    For $\mathrm{U}(1)$, the generator $T$ is simply the identity multiplied by a real scaling factor, often normalized such that $T=1/2$ in specific contexts (like spin systems), or $T=1$ when relating directly to the imaginary unit $i$ in the exponent. The…