Computing the lcs w.r.t. General EL+-TBoxes.

Recently, exact conditions for the existence of the least common subsumer (lcs) computed w.r.t. general EL-TBoxes have been devised [13]. This paper extends these results and provides necessary and suffcient conditions for the existence of the lcs w.r.t. EL-TBoxes. We show decidability of the existence in PTime and polynomial bounds on the maximal role-depth of the lcs, which in turn yields a computation algorithm for the lcs w.r.t. EL-TBoxes.