--- --- Calculation of the WCS Invariant on the Thurston Example (Section 4) --- def x~i := [| θ₁, θ₂, θ₃, θ₄ |]~i def g_i_j := [|[| 1, 0, 0, 0 |], [| 0, 1, 0, 0 |], [| 0, 0, κ / (sqrt β), (-1 * θ₂ * κ) / (sqrt β) |], [| 0, 0, (-1 * θ₂ * κ) / (sqrt β), ('(1 + θ₂) * κ) / (sqrt β) |]|] def g~i~j := [|[| 1, 0, 0, 0 |], [| 0, 1, 0, 0 |], [| 0, 0, '(1 + θ₂) / (κ * (sqrt β)), θ₂ / ((sqrt β) * κ) |], [| 0, 0, θ₂ / ((sqrt β) * κ), 1 / ((sqrt β) * κ) |]|] def β := '(1 + θ₂ - θ₂^2) def Γ~c_a_b := withSymbols [e] (1 / 2) * g~c~e . (∂/∂ g_b_e x~a + ∂/∂ g_a_e x~b - ∂/∂ g_a_b x~e) def R_i_j_k~l := withSymbols [a] ∂/∂ Γ~l_j_k x~i - ∂/∂ Γ~l_i_k x~j + Γ~l_i_a . Γ~a_j_k - Γ~l_j_a . Γ~a_i_k def R_i_j_k_l := withSymbols [a] R_i_j_k~a . g_a_l def J_a_b := [|[| 0, 1, 0, 0 |], [| -1, 0, 0, 0 |], [| 0, 0, 0, κ |], [| 0, 0, -1 * κ, 0 |]|] def J_a~c := J_a_b . g~b~c def ∇J_m_a_b := withSymbols [n] ∂/∂ J_a_b x~m + Γ~n_m_a . J_n_b + Γ~n_m_b . J_a_n def ∇J~m_a_b := withSymbols [t] ∇J_t_a_b . g~t~m def ∇J_m~a_b := withSymbols [t] ∇J_m_t_b . g~t~a def ∇J_m_a~b := withSymbols [t] ∇J_m_a_t . g~t~b def δ := generateTensor (\x y -> match (x, y) as (integer, integer) with | ($n, #n) -> 1 | (_, _) -> 0) [5, 5] def R'_i_j_k~l := generateTensor (\x y z w -> match (x, y, z, w) as (integer, integer, integer, integer) with | (#1, #1, _, _) -> 0 | (_, _, #1, #1) -> 0 | (#1, $b, #1, $d) -> -1 * p^2 * δ~(b - 1)_(d - 1) | ($a, #1, #1, $d) -> p^2 * δ~(a - 1)_(d - 1) | (#1, $b, $c, #1) -> p^2 * g_(b - 1)_(c - 1) | ($a, #1, $c, #1) -> -1 * p^2 * g_(a - 1)_(c - 1) | (#1, $b, $c, $d) -> -1 * p * ∇J_(b - 1)_(c - 1)~(d - 1) | ($a, #1, $c, $d) -> p * ∇J_(a - 1)_(c - 1)~(d - 1) | ($a, $b, #1, $d) -> -1 * p * ∇J~(d - 1)_(a - 1)_(b - 1) | ($a, $b, $c, #1) -> p * ∇J_(c - 1)_(a - 1)_(b - 1) | ($a, $b, $c, $d) -> R_(a - 1)_(b - 1)_(c - 1)~(d - 1) + -1 * p^2 * J_(b - 1)_(c - 1) * J_(a - 1)~(d - 1) + p^2 * J_(a - 1)_(c - 1) * J_(b - 1)~(d - 1) + 2 * p^2 * J_(a - 1)_(b - 1) * J_(c - 1)~(d - 1)) [5, 5, 5, 5] def S := withSymbols [i, j, k] let (es, os) := evenAndOddPermutations 5 in sum (map (\$σ -> R'_(σ 1)_j_1~i . R'_(σ 2)_(σ 3)_k~j . R'_(σ 4)_(σ 5)_i~k) es) - sum (map (\$σ -> R'_(σ 1)_j_1~i . R'_(σ 2)_(σ 3)_k~j . R'_(σ 4)_(σ 5)_i~k) os) S -- After 10 seconds calculation, we can get the following result: -- (1536 p^6 κ Sqrt[(1 + θ₂ - θ₂^2)]^16 - 1536 p^6 θ₂^2 κ Sqrt[(1 + θ₂ - θ₂^2)]^14 - 576 p^4 (1 + θ₂) κ Sqrt[(1 + θ₂ - θ₂^2)]^12 + 1536 p^6 (1 + θ₂) κ Sqrt[(1 + θ₂ - θ₂^2)]^14 + 8 p^2 (1 - 2 θ₂)^4 (1 + θ₂)^3 θ₂^2 κ - 88 p^2 (1 - 2 θ₂)^2 (1 + θ₂)^2 θ₂^2 Sqrt[(1 + θ₂ - θ₂^2)]^4 κ + 48 p^2 (1 - 2 θ₂)^3 (1 + θ₂)^2 θ₂^3 Sqrt[(1 + θ₂ - θ₂^2)]^2 κ - 12 p^2 (1 - 2 θ₂)^4 (1 + θ₂)^2 θ₂^4 κ - 24 p^2 (1 - 2 θ₂)^3 (1 + θ₂)^2 θ₂^2 κ Sqrt[(1 + θ₂ - θ₂^2)]^2 + 288 p^4 (1 - 2 θ₂)^2 (1 + θ₂)^2 θ₂^2 κ Sqrt[(1 + θ₂ - θ₂^2)]^6 - 160 p^2 (1 - 2 θ₂) (1 + θ₂) θ₂^3 Sqrt[(1 + θ₂ - θ₂^2)]^6 κ + 128 p^2 (1 - 2 θ₂)^2 (1 + θ₂) θ₂^4 Sqrt[(1 + θ₂ - θ₂^2)]^4 κ - 48 p^2 (1 - 2 θ₂)^3 (1 + θ₂) θ₂^5 Sqrt[(1 + θ₂ - θ₂^2)]^2 κ - 80 p^2 (1 - 2 θ₂)^2 (1 + θ₂) θ₂^3 Sqrt[(1 + θ₂ - θ₂^2)]^4 κ + 768 p^4 (1 - 2 θ₂) (1 + θ₂) θ₂^3 Sqrt[(1 + θ₂ - θ₂^2)]^8 κ + 8 p^2 (1 - 2 θ₂)^4 (1 + θ₂) θ₂^6 κ + 24 p^2 (1 - 2 θ₂)^3 (1 + θ₂) θ₂^4 κ Sqrt[(1 + θ₂ - θ₂^2)]^2 - 288 p^4 (1 - 2 θ₂)^2 (1 + θ₂) θ₂^4 κ Sqrt[(1 + θ₂ - θ₂^2)]^6 + 112 p^2 (1 - 2 θ₂) (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^6 θ₂^2 κ + 20 p^2 (1 - 2 θ₂)^2 (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^4 θ₂^2 κ - 64 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^8 θ₂^4 κ + 96 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^6 θ₂^5 (1 - 2 θ₂) κ - 56 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^4 θ₂^6 (1 - 2 θ₂)^2 κ - 80 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^6 θ₂^4 (1 - 2 θ₂) κ + 384 p^4 Sqrt[(1 + θ₂ - θ₂^2)]^10 θ₂^4 κ + 16 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^2 θ₂^7 (1 - 2 θ₂)^3 κ + 40 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^4 θ₂^5 (1 - 2 θ₂)^2 κ - 384 p^4 Sqrt[(1 + θ₂ - θ₂^2)]^8 θ₂^5 (1 - 2 θ₂) κ + 32 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^8 θ₂^3 κ + 24 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^6 θ₂^3 (1 - 2 θ₂) κ - 448 p^4 Sqrt[(1 + θ₂ - θ₂^2)]^10 θ₂^3 κ - 2 p^2 (1 - 2 θ₂)^4 θ₂^8 κ - 8 p^2 (1 - 2 θ₂)^3 θ₂^6 κ Sqrt[(1 + θ₂ - θ₂^2)]^2 + 96 p^4 (1 - 2 θ₂)^2 θ₂^6 κ Sqrt[(1 + θ₂ - θ₂^2)]^6 - 10 p^2 (1 - 2 θ₂)^2 θ₂^4 Sqrt[(1 + θ₂ - θ₂^2)]^4 κ - 16 p^2 (1 + θ₂)^3 (1 - 2 θ₂)^3 Sqrt[(1 + θ₂ - θ₂^2)]^2 θ₂ κ + 64 p^2 (1 + θ₂)^2 (1 - 2 θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^6 θ₂ κ + 40 p^2 (1 + θ₂)^2 (1 - 2 θ₂)^2 Sqrt[(1 + θ₂ - θ₂^2)]^4 θ₂ κ - 384 p^4 (1 + θ₂)^2 (1 - 2 θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^8 κ θ₂ + 96 p^2 (1 + θ₂) θ₂^2 Sqrt[(1 + θ₂ - θ₂^2)]^8 κ - 32 p^2 (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^8 θ₂ κ - 24 p^2 (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^6 θ₂ (1 - 2 θ₂) κ + 448 p^4 (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^10 κ θ₂ - 32 p^2 (1 - 2 θ₂) (1 + θ₂)^2 Sqrt[(1 + θ₂ - θ₂^2)]^6 κ - 10 p^2 (1 - 2 θ₂)^2 (1 + θ₂)^2 Sqrt[(1 + θ₂ - θ₂^2)]^4 κ + 8 p^2 (1 - 2 θ₂)^3 (1 + θ₂)^3 Sqrt[(1 + θ₂ - θ₂^2)]^2 κ + 16 p^2 (1 - 2 θ₂)^2 (1 + θ₂)^3 κ Sqrt[(1 + θ₂ - θ₂^2)]^4 - 2 p^2 (1 - 2 θ₂)^4 (1 + θ₂)^4 κ - 96 p^4 (1 - 2 θ₂)^2 (1 + θ₂)^3 κ Sqrt[(1 + θ₂ - θ₂^2)]^6 + 4 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^6 (1 + θ₂) (1 - 2 θ₂) κ + 8 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^8 (1 + θ₂) κ - 112 p^4 Sqrt[(1 + θ₂ - θ₂^2)]^10 κ (1 + θ₂) - 8 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^8 θ₂^2 κ - 4 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^6 θ₂^2 (1 - 2 θ₂) κ + 112 p^4 Sqrt[(1 + θ₂ - θ₂^2)]^10 θ₂^2 κ - 48 p^2 (1 - 2 θ₂)^2 (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^6 θ₂ κ + 40 p^2 (1 - 2 θ₂)^3 (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^4 θ₂^2 κ + 12 p^2 (1 - 2 θ₂)^2 (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^6 κ - 20 p^2 (1 - 2 θ₂)^3 (1 + θ₂)^2 Sqrt[(1 + θ₂ - θ₂^2)]^4 κ + 112 p^2 (1 - 2 θ₂)^2 (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^6 θ₂^2 κ + 32 p^2 (1 - 2 θ₂) (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^8 κ - 32 p^2 (1 - 2 θ₂)^2 (1 + θ₂)^2 Sqrt[(1 + θ₂ - θ₂^2)]^6 κ + 40 p^2 (1 - 2 θ₂)^3 (1 + θ₂)^2 Sqrt[(1 + θ₂ - θ₂^2)]^4 θ₂ κ - 21 p^2 (1 - 2 θ₂)^4 (1 + θ₂)^2 Sqrt[(1 + θ₂ - θ₂^2)]^2 θ₂^2 κ + 7 p^2 (1 - 2 θ₂)^4 (1 + θ₂)^3 Sqrt[(1 + θ₂ - θ₂^2)]^2 κ - 80 p^2 (1 - 2 θ₂)^3 (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^4 θ₂^3 κ + 21 p^2 (1 - 2 θ₂)^4 (1 + θ₂) θ₂^4 Sqrt[(1 + θ₂ - θ₂^2)]^2 κ - 32 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^8 θ₂^2 (1 - 2 θ₂) κ + 48 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^6 θ₂^3 (1 - 2 θ₂)^2 κ - 16 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^10 θ₂^2 κ + 64 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^8 θ₂^3 (1 - 2 θ₂) κ - 80 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^6 θ₂^4 (1 - 2 θ₂)^2 κ + 40 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^4 θ₂^5 (1 - 2 θ₂)^3 κ - 20 p^2 (1 - 2 θ₂)^3 θ₂^4 Sqrt[(1 + θ₂ - θ₂^2)]^4 κ - 12 p^2 (1 - 2 θ₂)^2 θ₂^2 Sqrt[(1 + θ₂ - θ₂^2)]^6 κ - 7 p^2 (1 - 2 θ₂)^4 θ₂^6 Sqrt[(1 + θ₂ - θ₂^2)]^2 κ - 64 p^4 (1 + θ₂)^2 Sqrt[(1 + θ₂ - θ₂^2)]^10 κ - 32 p^2 (1 + θ₂)^2 Sqrt[(1 + θ₂ - θ₂^2)]^8 κ + 16 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^10 (1 + θ₂) κ - 64 p^2 Sqrt[(1 + θ₂ - θ₂^2)]^8 (1 - 2 θ₂) θ₂ (1 + θ₂) κ + 576 p^4 θ₂ Sqrt[(1 + θ₂ - θ₂^2)]^12 κ - 144 p^4 Sqrt[(1 + θ₂ - θ₂^2)]^12 κ - 224 p^4 (1 - 2 θ₂)^2 κ Sqrt[(1 + θ₂ - θ₂^2)]^10 (1 + θ₂) - 384 p^4 κ (1 - 2 θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^12 θ₂ + 224 p^4 (1 - 2 θ₂)^2 θ₂^2 κ Sqrt[(1 + θ₂ - θ₂^2)]^10 + 192 p^4 (1 - 2 θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^12 κ + 128 p^4 Sqrt[(1 + θ₂ - θ₂^2)]^14 κ - 320 p^4 θ₂^2 Sqrt[(1 + θ₂ - θ₂^2)]^10 κ (1 + θ₂) + 128 p^4 (1 - 2 θ₂) (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^10 κ - 128 p^4 θ₂^2 (1 - 2 θ₂) κ Sqrt[(1 + θ₂ - θ₂^2)]^10 + 192 p^4 (1 + θ₂)^2 (1 - 2 θ₂) κ Sqrt[(1 + θ₂ - θ₂^2)]^8 - 384 p^4 θ₂^2 (1 - 2 θ₂) (1 + θ₂) κ Sqrt[(1 + θ₂ - θ₂^2)]^8 + 192 p^4 θ₂^4 Sqrt[(1 + θ₂ - θ₂^2)]^8 κ (1 - 2 θ₂) - 256 p^4 θ₂ Sqrt[(1 + θ₂ - θ₂^2)]^10 κ (1 - 2 θ₂) (1 + θ₂) + 256 p^4 θ₂^3 Sqrt[(1 + θ₂ - θ₂^2)]^10 κ (1 - 2 θ₂) + 128 p^4 θ₂^2 (1 - 2 θ₂)^2 κ (1 + θ₂) Sqrt[(1 + θ₂ - θ₂^2)]^8 - 64 p^4 θ₂^4 (1 - 2 θ₂)^2 κ Sqrt[(1 + θ₂ - θ₂^2)]^8 - 64 p^4 (1 - 2 θ₂)^2 (1 + θ₂)^2 κ Sqrt[(1 + θ₂ - θ₂^2)]^8)/(16 Sqrt[(1 + θ₂ - θ₂^2)]^16) -- The above result is simplified using the Wolfam language as follows: -- (p^2 (-25 - 640 p^2 (1 + θ₂- θ₂^2)^2 + 3072 p^4 (1 + θ₂ - θ₂^2)^4) κ) / (16 (1 + θ₂ - θ₂^2)^4)