# Need help understanding Math notation

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MrDoDo    122
I'm sorry if this is more apt in the math section but I couldn't be sure. I'm working on a project and it involves implementation of a frequency algorithm in O(n). I've come accross a paper I'm very interested in, but my math is speckled, and I just don't know how to interpret this: |K| Where K is a set of individual, distinct symbols. Worth noting is that there is an array of integers which essentially holds a 'count' for each of these symbols. I've tried searching I really have but find nothing concise. Everything at my disposal points to magnitude, which doesn't really apply. As far as I can see. The paper in question can be found at http://www.cs.umd.edu/~samir/498/karp.pdf

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tompko    122
For sets |K| would be the size of the set K. i.e. the number of elements inside it. Having glanced over the paper this certainly seems to be the case here.

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MrDoDo    122
Thank you very much. I'll continue my path on that assumption.

Good day to you.

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ToohrVyk    1596
In general, |x| is used to denote the size of x. So |x| for reals is the absolute value, |x| for complex numbers is the length, |x| for vectors is also the length (using whatever length function is assumed by default), and |x| for sets is the cardinal (that is, the number of elements, or an infinite cardinal set).