+-- | We know what (c t6 2 1 0 0) should be from Sorokina and Zeilfelder, p. 87.
+prop_c_tilde_2100_correct :: Cube -> Bool
+prop_c_tilde_2100_correct cube =
+ c t6 2 1 0 0 == (3/8)*int + (1/12)*(f + r + l + b) + (1/64)*(ft + rt + lt + bt)
+ + (7/48)*t + (1/48)*d + (1/96)*(fr + fl + br + bl)
+ + (1/192)*(fd + rd + ld + bd)
+ where
+ t6 = tetrahedron6 cube
+ fvs = Tetrahedron.fv t6
+ int = interior fvs
+ f = front fvs
+ r = right fvs
+ l = left fvs
+ b = back fvs
+ ft = front_top fvs
+ rt = right_top fvs
+ lt = left_top fvs
+ bt = back_top fvs
+ t = top fvs
+ d = down fvs
+ fr = front_right fvs
+ fl = front_left fvs
+ br = back_right fvs
+ bl = back_left fvs
+ fd = front_down fvs
+ rd = right_down fvs
+ ld = left_down fvs
+ bd = back_down fvs
+