Is there a way to set arbitrary function commuting rules?
I am trying to perform a derivation using discrete difference operations, but I don't want to actually define my discrete operator. What I would like to do, is specify
d = function('d') var('x y')
I'd like to specify d(xy) = d(xy) (multiplication does not commute), but I need d(x+y) = d(x) + d(y) (addition does commute). Any ideas?