Further results on strong edge-colourings in outerplanar graphs

An edge-colouring is strong if every colour class is an induced matching. In this work we give a formula that determines either the optimal or the optimal plus one strong chromatic index of bipartite outerplanar graphs. Further, we give an improved upper bound for any outerplanar graph which is close to optimal. All our proofs yield efficient algorithms to construct such colourings.