This a probably very easy question and I am not sure whether it has been asked before (although I searched for it). Moreover I really hope this is nothing which can be found in any standard commutative algebra text book.




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Is there a thorough discussion of Taylor expansions of polynomials (or maybe rational functions) with coefficients in an arbitrary field? 




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Problem:
In the classical Taylor expansion we have coefficients of the form $\frac{1}{n!}$, which obviously don't have to exists in any field, say, of finite characteristic.


Motivation:
I came across it at a discussion of the Zariski tangent space to a scheme $X$ at a point $y$. Say $X=\mathbb A\_k^n$ and $y\in X$ corresponds to the maximal ideal $\frak m$. Then the differential $D\_y$ induces an isomorphism $\frak {m}/\frak {m}^2\rightarrow E^\vee$, where $\frak E^\vee$ is the dual of the vector space $k^n$, thus identifies the Zariski tangent space with the "classical" tangent space as we know it from the theory of manifolds.


The prove usually involves something like: $\frak {m}=(T\_1-\lambda\_1,..., T\_n-\lambda\_n)$, then use the Taylor expansion of any polynomial $P$ in $(\lambda\_1,...,\lambda\_n)$.


Remark: I guess this is easy to fix for polynomials, but I wonder whether everything works in general for say rational functions, or anything fancier.



(algebraic) Taylor expansion for polynomials (rational functions) with coefficients in an arbitrary field.
I found the answer myself - thanks to the comment by KConrad. Apparently everything can be fixed with the hasse derivative <http://math.fontein.de/2009/08/12/the-hasse-derivative/>. Thanks for your help.


