Right, linearity is not preserved. In the paper (pdf available online), there's a discussion of differential equations under this notion; I guess its utility will depend on one's perspective. Kerry -- lkmitch@att.net www.fractalus.com/kerry

Then we have 2' + 3' = 1 + 1 = 2, (2+3)' = 5' = 1. So ' is not linear. Does this notion lead to something further, or is it a dead end?

Gene