I'm having trouble specifying the pattern to pick out terms from a polynomial.
For example, if the polynomial were 2z-2w + 4x-4y+3a, I want to specify a
pattern to pick out 2z-2w and 4x-4y; in general, I want to pick out an
expression like n*x_-n*y_. I tried the pattern, x_Integer*y_ - x_Integer*z_, but
this did not work. How do I specify such a pattern?