... PQ-tree¹

Of course, one has to modify the algorithm of [1] to detect upon reducing T with S_i, whether it is possible that there are no errors in S_i nor in the sets already in T.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.