List: A Specialization of Collection

INSERT:

if C is a list: V is the first element in C'.

DELETE:

if C is a list: it is the first occurrence of V in C that is deleted.

JOIN:

if C1 and C2 are both lists: in C1' the elements of C1 and C2 are in their original order, and the elements of C1 are before the elements of C2.

MAP:

if C is a list: if E1 occurs before E2 in C, then the call P(E1) is made before the call P(E2).

Specification of Window

• Every window is on an element. No such thing as an `empty' window.