We say that a function $ f:{\mathbb Z}\times {\mathbb Z} \to {\mathbb Z}$ has bounded neighbor-difference if there is an integer $ K\in\mathbb{N}$ such that for all $ x,y\in{\mathbb Z}$ we have $ $ |f(x,y) – f(x+1,y)| \leq K \text{ and } |f(x,y) – f(x,y+1)| \leq K.$ $ Is it possible that a function $Read more