Without prethought, I mentioned in class once that the reason the symbol $\partial$ is used to represent the boundary operator in topology is that its behavior is akin to a derivative. But after reflection and some research, I find little support for my unpremeditated claim. Just sticking to the topological boundary (as opposed to the boundary of a manifold or of a simplicial chain), $\partial^3 S = \partial^2 S$ for any set $S$. So there seems to be no possible analogy to Taylor series. Nor can I see an analogy with the fundamental theorem of calculus. The only tenuous sense in which I can see the boundary as a derivative is that $\partial S$ is a transition between $S$ and the "background" complement $\overline{S}$. I've looked for the origin of the use of the symbol $\partial$ in topology without luck. I have only found [references][1] for its use in calculus. I've searched through _History of Topology_ (Ioan Mackenzie James) online without success (but this may be my poor searching). Just visually scanning the 1935 _Topologie_ von Alexandroff und Hopf, I do not see $\partial$ employed. I have two questions: > <b>Q1</b>. Is there a sense in which the boundary operator $\partial$ is analogous to a derivative? > <b>Q2</b>. What is the historical origin for the use of the symbol $\partial$ in topology? Thanks! [1]: http://en.wikipedia.org/wiki/%E2%88%82