If w i ∈ S 1 , then under the assumption that incomplete edges are extended from left-toright (see footnote 1), the incomplete edge should  be discarded, because any completed edges that could result from extending that incomplete edge would have the same start position, i.e., the chart cell would be (i, k) for some k>i, which is closed to the completed edge.
if w i ∈ S 1 , then w j ∈ E 1 .