“…More recently, with arbitrary seminorms or more general convex functionals, the term SSP (strong stability preserving) -introduced in [5] -has become popular. Related work for nonlinear problems was done in [16,17,20,24] for contractivity, where one considers ũ n − u n with differences of two numerical solutions instead of u n as in (1.7). Finally we mention that related results on nonnegativity preservation and contractivity or monotonicity for linear problems were derived already in [1,22], again for methods with all a j , b j ≥ 0 and with ∆t ≤ c τ 0 .…”