Title: Reduction of coKähler and 3-cosymplectic manifolds

Abstract: The notion of coK\"{a}hler manifolds (resp. 3-cosymplectic manifolds) is an odd-dimensional analogue of the one of K\"{a}hler manifolds (resp. hyperK\"{a}hler manifolds). In this paper, we obtain reduction theorems of coK\"{a}hler manifolds and 3-cosymplectic manifolds. We prove that K\"{a}hler and coK\"{a}hler reductions have a natural compatibility with respect to cone constructions, that is, the coK\"{a}hler quotient of the cone of a K\"{a}hler manifold (resp. the K\"{a}hler quotient of the cone of a coK\"{a}hler manifold) coincides with the cone of the K\"{a}hler quotient (resp. the cone of the coK\"{a}hler quotient). We also show that hyperK\"{a}hler and 3-cosymplectic reductions admit the compatibility with respect to cone constructions. We further prove that the compatibility of K\"{a}hler and coK\"{a}hler reductions with respect to mapping torus constructions also does hold.