“…The same problem for n = 4 was undertaken in [4]. In a very recent work, an extension to n + 1-dimensional case for n > 2 of the group classification problem for linear evolution equations has been carried out in [5] where the authors solved the problem in full generality and compared their results with those of n = 3 of [1] (also for n = 4 of [4]) commented that there is a redundant case, where A(x) = a ∈ R, B(x) = 0 with generators ∂ t , ∂ x , t∂ t + 1/3(x − 2at)∂ x corresponding to N = 6 in [1]), that can be removed by an equivalence transformation (in fact a simple Galilei transformation (t, x, u) → (t, x + at, u) is sufficient to set a = 0) and an omission of a constraint on one of the coefficients of the generators. Above, in Table 1, we reproduce the group classification table with the necessary corrections made.…”