  Suppose that A is a subset of an abelian group G. To know the 3-deck of A is
to know the number of occurences in A of translates of each possible multiset
{0,a,b}. The concept of the 3-deck is naturally extended to integrable
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.
