Sumset Explained

In additive combinatorics, the sumset (also called the Minkowski sum) of two subsets

A

and

B

of an abelian group

G

(written additively) is defined to be the set of all sums of an element from

A

with an element from

B

. That is,

A+B=\{a+b:a\inA,b\inB\}.

The

n

-fold iterated sumset of

A

is

nA=A++A,

where there are

n

summands.

Many of the questions and results of additive combinatorics and additive number theory can be phrased in terms of sumsets. For example, Lagrange's four-square theorem can be written succinctly in the form

4\Box=N,

where

\Box

is the set of square numbers. A subject that has received a fair amount of study is that of sets with small doubling, where the size of the set

A+A

is small (compared to the size of

A

); see for example Freiman's theorem.

See also

References

. Henry Mann . Henry Mann . Addition Theorems: The Addition Theorems of Group Theory and Number Theory . Robert E. Krieger Publishing Company . Huntington, New York . 1976 . Corrected reprint of 1965 Wiley . 0-88275-418-1 .

External links