theorem T_cross_sectional {eps_i eps_j dHi dHj T mu : ℝ}
(hdH : dHi ≠ dHj)
(hFOC_i : eps_i = T * dHi + mu)
(hFOC_j : eps_j = T * dHj + mu) :
T = (eps_i - eps_j) / (dHi - dHj) := by
have h : eps_i - eps_j = T * (dHi - dHj) := by linarith
rw [h, mul_div_cancel_right₀ T (sub_ne_zero.mpr hdH)]Results 36-46: Conservation Laws and Symmetry Identities