% box(or(P,diam(Q))) = or(box(P),diam(Q)).

'$equiv'('$box'('$or'(p,'$diam'(q))),'$or'('$box'(p),'$diam'(q)))-w -> [].

:-option(term_var_weight_gt_small).


/*
Takes too long. When we split it into two halves,
cf. th11 and th12, it's ok.
*/