Equation Icon  ∑n j ∂ ut = A ∂xju + F (t,x ), x ∈ Σ, t ≥ 0, (5.50 ) j=1 u(0,x ) = 0, x ∈ Σ, (5.51 ) bu = g(t,x), x ∈ ∂Σ, t ≥ 0, (5.52 )