**Key observation.** An enumeration algorithm may not
have to store all output in the active memory. Some algorithm can simply
dump each output object *y* without storing it.

This fact motivates us to define:

**Compact algorithm**

A *compact* algorithm for
is one which solves, for , in space
polynomial in both input size |*x*| and
the largest size |*y*| of output objects *y*.

**Class CEP** (a subclass of EP)

is in *CEP* if
a compact polynomial algorithm for .

Wed Jun 12 17:26:21 GMT+0100 1996