3-Transposition Groups of Symplectic Type and Vertex Operator Algebras

The 3-transposition groups that act on a vertex operator algebra in the way described by Miyamoto are classified under the assumption that the group is centerfree and the VOA carries a positive-definite invariant Hermitian form. This generalizes and refines the result of Kitazume and Miyamoto. Application to a similar but different situation is also considered in part by a slight generalization of the argument.