(OK, I guess it's better to re-subscribe to the list). In reply to Norbert Thiebaud*:
In the Power rule, which *is* commonly used for differentiation, we take a series of polinomials where n !=0. n is not only different than zero, most importantly, it is a constant. Of course we can use the power function a^b in your spreadsheet when the b is a constant but you have to understand the assumptions being made before blindingly applying formulas, and we just can't assume every speadsheet user will use a restricted set of capabilities. Now, in a spreadsheet this formula would be used if you have a polinomial and you want to calculate and/or graph it's derivative. Since we don't do symbolic math in the speadsheet you would actually do this by hand and you would resolve the trivial constant^0 cases. In the case of the set theory book, do note that the author is constructing his own algebra, and it's natural that he might not want indefinite values that get outside his set: 0^0 and x/0 are such cases. The text is not a demonstration, it is simply a statement taken out of context. I guess looking hard it may be possible to find an elaborated case where someone manages to shoot himself in the foot but ultimately I would wonder. if this author *is* using mathematics correctly. 0^0 is a good indication that there is something wrong in your calculation and evidently Excel users have come to accept it. Pedro. *Welcome to this list ;).
