For the Viterbi alignments, only three results could be generated (one for each symmetrization method).
a multiple citance alignment (MCa) is an equivalence relation ∼ ij ∼ ij + on the set i c i , which is the transitive closure of the union of all pairwise alignments of citance pairs in G. Taking the transitive closure and not only the union of all pairwise alignments ensures that the MCa is an equivalence relation.