hi,

according to http://topdefinitions.com/multisets-and-their-operations/ the difference between multisets is defined as: The difference of two multisets A and B, is a multiset such that the multiplicity of an element is equal to the multiplicity of an element in A minus multiplicity of an element in B, if the difference is +ve, and it is equal to 0 if the difference is 0 and –ve. It is denoted by A-B.

e.g. A={l,l,m,m,m,n,n} B={l,m,m,n,n,n}

A-B={l,m}

however in pike:

multiset A =(< "l","l","m","m","m","n","n">); multiset B =(< "l","m","m","n","n","n">); A-B;

Result: (< >)

greetings, martin.