//A \emph{complete extension} is ...


? dummy:
dummy() &
~ ? s: ? defended_by_s: ? attacked_by_s: 
    (?N: in_test(N) & ~s(N)) & 
    ( ! N: in_node(N) => (attacked_by_s(N) <=> ( ? M: in_attack(M,N) & s(M) ) )) &
	( ! N: in_node(N) => (defended_by_s(N) <=> ( ! M: in_attack(M,N) => attacked_by_s(M) ) ) ) &  
	(! N: in_node(N) => ( s(N) <=> defended_by_s(N)) ) &
	~ ? N: ? M: in_attack(N,M) &  s(N) &  s(M).

