“…We present a Hubert space treatment for proving existence and uniqueness in the Cauchy problem for a general linear 2A>parabolic differential operator. We shall follow in rough outline the Hubert space approach to the Cauchy problem for parabolic operators of the form P = |-£(0 = |-2 "Áx*t)D", where L(t) is uniformly strongly elliptic on 7?n (here x = (xx,..., xn}, «=<«!,...,«">, |«| =<*!+• ••+«", and Da = ((lli) 8l8Xl)"i-■ -((l/i) 8l8xny»), as given in [5]. As in [5] we shall make use of the Hubert spaces Jfr'$ (=äS2k in the notation of [4,Chapter II], where k(£, r)=A:r,s(í, t) is the temperate weight function defined for <£ r>=<fi,..., £n, r> e R»'+1 by *,..(£ r)=ßU *M£)-Here #(i) = {l + |f|2}1/2, with |f|2 = 2?=i if, is the usual elliptic weight function in Rn and Q(£, T) = {r2+q4k($)}llik).…”