PrimSig dir1 = makeSig(dir, "D1", false, true);
PrimSig dir2 = makeSig(dir, "D2", false, true);
fact = file1.join(parent).equal(dir1).and(fact);
fact = file2.join(parent).equal(dir2).and(fact);
fact = file3.join(parent).equal(dir2).and(fact);
fact = dir2.join(parent).equal(dir1).and(fact);
fact = dir1.join(parent).equal(root).and(fact);
}
/* Here is instance number 2. */