Its a concept in topology and real analysis: See here
What does it mean "accumulation point". Used in the following theorem. If two holomorphic functions in a region agree at a set of points with an accumulation point in then on .
What does that mean? The book assumes the reader knows what "accumulation" means.
In a literary sense, accumulation means 'build-up' .. ie, an accumulation of dust had built up on ThePerfectHacker's bar of soap (sorry )
However, I'm unsure whether or not it has a seperate specialist mathematical meaning.
After a quick Google search (always recommended ), I come across this:
Accumulation point (mathematics - encyclopedia article about Accumulation point (mathematics.)
I apologise if this doesn't help, but I'm weary of saying more than this, but I'd rather just give you the information rather than risk giving you wrong opinionsA prototypical example of a limit point is an accumulation point, which is a limit of a sequence.
Types of limit points
If every open set containing x contains infinitely many points of S then x is a specific type of limit point called a ω-accumulation point of S.
If every open set containing x contains uncountably many points of S then x is a specific type of limit point called a condensation point of S.
Somebody else should be able to give more specific information.
If infinitely many numbers are given in a finite interval, these numbers possess at least 1 point of accumulation. That is, at least 1 point such that in every interval about the point , however small there lie infinitely many of the given numbers. Its sort of like a Dekedind cut.
Example: Subdivide the interval [0,1] into 10 equal parts (0.1 ... 0.9). One of the sub-intervals must contain infinitely many numbers. Choose this interval to be [0.1, 0.2]. Now subdivide this interval into 10 equal parts. Clearly, we find that there is an accumulation point.
So you eventually get the point of accumulation to be P = 0.a1a2a3....
I'm not sure about the theorem as you've stated it. Here is another version from here. Two holomorphic functions that agree at every point of an infinite set with an accumulation point inside the intersection of their domains also agree everywhere in some open set.
The theorem says essentially that two holomorphic functions that are equal on any set with a non-isolated point are equal "everywhere."