>>12258352it's obviously not linear. pick any fucking sequence whatsoever, x[n]. then y[0] = 1. but then 2*x[n] gets sent to a sequence which also evaluates to 1 at 0. if x -> y were linear, then 2*x[n] would have to get sent to a sequence which evaluates at 0 to 2*y[0] = 2. this doesn't happen.
this is the point of nonlinearity, if your map defined y[0] = 0 instead of y[0] = 1 then it would be linear.
