Separation of variables : split

split takes two arguments : an expression depending on two variables and the list of these two variables.
If the expression may be factorized into two factors where each factor depends only of one variable, split returns the list of this two factors, otherwise it returns the list [0].
Input :

split((x+1)*(y-2),[x,y])

Or :

split(x*y-2*x+y-2,[x,y])

Output :

[x+1,y-2]

Input :

split((x^2*y^2-1,[x,y])

Output :

[0]