Additive number theory is currently an active field related to combinatorics. In this paper we give a survey of problems and results concerning lower bounds for cardinalities of various restricted sumsets with elements in a field or an abelian group.
Erdős-Heilbronn conjecture and the polynomial methodLet A = {a 1 , . . . , a k } and B = {b 1 , . . . , b l } be two finite subsets of Z with a 1 < · · · < a k andwhence we see that the sumset A + B = {a + b: a ∈ A and b ∈ B} contains at least k + l − 1 elements. In particular, |2A| 2|A| − 1, where |A| denotes the cardinality of A, and 2A stands for A + A.The following fundamental theorem was first proved by A. Cauchy [9] in 1813 and then rediscovered by H. Davenport [11]
in 1935.Cauchy-Davenport Theorem. Let A and B be non-empty subsets of the field Z/pZ where p is a prime. Then |A + B| min{p, |A| + |B| − 1}.(1.1)For lots of important results on sumsets over Z, the reader is referred to the recent book [38] by T. Tao and V. H. Vu. In this paper we mainly focus our attention on restricted sumsets with elements in a field or an abelian group.In combinatorics, for a finite sequence {A i } n i=1 of sets, a sequence {a i } n i=1 is called a system of distinct representatives of {A i } n i=1 if a 1 ∈ A 1 , . . . , a n ∈ A n and a 1 , . . . , a n are distinct. A fundamental theorem of P. Hall [17] states that {A i } n i=1 has a system of distinct Supported by the National Science Fund (No. 10425103) for Distinguished Young Scholars in China.