Editing Combinatorics (section)

===Arithmetic combinatorics===
{{Main|Arithmetic combinatorics}}

Arithmetic combinatorics arose out of the interplay between [[number theory]], combinatorics, [[ergodic theory]], and [[harmonic analysis]]. It is about combinatorial estimates associated with arithmetic operations (addition, subtraction, multiplication, and division). [[Additive number theory]] (sometimes also called additive combinatorics) refers to the special case when only the operations of addition and subtraction are involved.  One important technique in arithmetic combinatorics is the [[ergodic theory]] of [[dynamical system]]s.