Knots with g(E(K))=2 and g(E(K#K#K))=6 and Morimoto's Conjecture

We show that there exist knots K⊂S3 with g(E(K))=2 and g(E(K#K#K))=6. Together with [Tsuyoshi Kobayashi, Yo'av Rieck, On the growth rate of the tunnel number of knots, J. Reine Angew. Math. 592 (2006) 63–78, Theorem 1.5], this proves existence of counterexamples to Morimoto's Conjecture [Kanji Morimoto, On the super additivity of tunnel number of knots, Math. Ann. 317 (3) (2000) 489–508]. This is a special case of [Tsuyoshi Kobayashi, Yo'av Rieck, Knot exteriors with additive Heegaard genus and Morimoto's Conjecture, Algebr. Geom. Topol. 8 (2008) 953–969, preprint version available at http://arxiv.org/abs/math.GT/0701765, 2007].