module early.

accumulate core.

% E-input:
one (in X M)  (pair (ii X W)  (M W)). 

% E-com
one (par P Q) (pair tau (par Px Qx)) :- 
  one P (pair (oo X Y) Px), one Q (pair (ii X Y) Qx);
  one P (pair (ii X Y) Px), one Q (pair (oo X Y) Qx).