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Notes

Chapter 10 — Worked Examples

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  1. #1
    gth(i,j)=ei(αt(i,j)+φiφj).g_t^h(i,j)=e^{i(\alpha_t(i,j)+\varphi_i-\varphi_j)}.
  2. #2

    For triangle :

    Ωt(i,j,k)=ei(αij+αjk+αki).\Omega_t(i,j,k)=e^{i(\alpha_{ij}+\alpha_{jk}+\alpha_{ki})}.
  3. #3

    For triangle : Discrete curvature:

    ωt(i,j,k)=2(1cos(αij+αjk+αki)).\omega_t(i,j,k)=2\bigl(1-\cos(\alpha_{ij}+\alpha_{jk}+\alpha_{ki})\bigr).
  4. #4
    EF(φ)=i,jFWt(i,j)>0Wt(i,j)2(1cos(αij+φiφj)).\mathcal{E}_{F^\circ}(\varphi)=\sum_{\substack{i,j\in F^\circ\\W_t(i,j)>0}}W_t(i,j)\cdot 2\bigl(1-\cos(\alpha_{ij}+\varphi_i-\varphi_j)\bigr).
  5. #5

    In the small-curvature regime, the normal equations give:

    Lφ=Bdiag(W)α,φ=LBdiag(W)α+c1L\,\varphi^*=-B\,\mathrm{diag}(W)\,\alpha,\qquad\varphi^*=-L^\dagger B\,\mathrm{diag}(W)\,\alpha+c\cdot\mathbf{1}
  6. #6
    α~ij=αij+φiφj,ρ(i)=jiWt(i,j)α~ij2.\tilde\alpha_{ij}=\alpha_{ij}+\varphi_i^*-\varphi_j^*,\qquad\rho(i)=\sum_{j\sim i}W_t(i,j)\,\tilde\alpha_{ij}^2.
  7. #7

    Incidence matrix for on (edges ordered as ):

    B=(110101011),W=diag(8,8,8)=8I.B=\begin{pmatrix}-1&1&0\\-1&0&1\\0&-1&1\end{pmatrix},\quad W=\mathrm{diag}(8,8,8)=8I.
  8. #8

    Existence of Fruit B:

    Existence({7,8,9,10},t)=([g~B]Gconst,  {8},  {0.6})\mathrm{Existence}(\{7,8,9,10\},t)=\bigl([\tilde g|_{B^\circ}]_{\mathcal{G}_{\mathrm{const}}},\;\{8\},\;\{0.6\}\bigr)
  9. #9

    with:

    g(1,2)=eiπσx/4,g(2,3)=eiπσy/4,g(3,1)=eiπσz/4g(1,2)=e^{i\pi\sigma_x/4},\quad g(2,3)=e^{i\pi\sigma_y/4},\quad g(3,1)=e^{i\pi\sigma_z/4}