“…Then we deduce from above that Φ(x, t) satisfies integral identity (11), that is, Φ is a unique solution of problems ( 8)- (10) in C 0 (Λ T , L 2 (X)) in the meaning of Definition 2. Also, since w = Φ − z, it is written that f or any t ∈ Λ T by (25). Also, since g(s, t) = 2 χ (u(s, t) − κ(s, t)), we can easily say that function Φ provides estimate (72), which completes the proof.…”