Suppose that A is a subset of an abelian group G. To know the 3-deck of A is to know the number of occurrences in A of translates of each possible multiset {0,a,b}. The concept of the 3-deck of a set is naturally extended to L¹ functions on G. In this paper we study when the 3-deck of a function determines the function up to translations. The method is to look at the Fourier Transform of the function. Our emphasis is on the real line and the cyclic groups.

Research partially financed by: European Commission Harmonic Analysis and Related Problems 2002-2006 IHP Network (Contract Number: HPRN-CT-2001-00273 - HARP)