}
if (op == ExprQt.Op.LONE) {
QuantifiedFormula p1 = (QuantifiedFormula) visit_qt(ExprQt.Op.ALL, xvars, sub);
QuantifiedFormula p2 = (QuantifiedFormula) visit_qt(ExprQt.Op.ALL, xvars, sub);
Decls s1 = p1.decls(), s2 = p2.decls(), decls = null;
Formula f1 = p1.formula(), f2 = p2.formula();
Formula[] conjuncts = new Formula[s1.size()];
for(int i=0; i<conjuncts.length; i++) {
kodkod.ast.Decl d1 = s1.get(i), d2 = s2.get(i);
conjuncts[i] = d1.variable().eq(d2.variable());
if (decls==null) decls = d1.and(d2); else decls = decls.and(d1).and(d2);