“…We choose c(t) ≥ 0 large enough so that the functions u −→ uf ± (u) are strictly increasing on the interval [min(u 0 (., ))−η, max(u 0 (., ))+ η] ∀ , with η > 0 fixed arbitrary. This is possible as proved in (23)(24)(25) since the interval [min(u 0 (., )) − η, max(u 0 (., )) + η] is bounded therefore (4) suffices to ensure that f is Lipschitz continuous in this interval with fixed Lipschitz constant. We approximate u 0 ∈ L ∞ (T) by continuous functions u 0 (., ) in L ∞ norm.…”