Special symmetry classesActionsEnumeration of symmetry classesThe involution principle

The involution principle

We have evaluated the number of graphs on v vertices by examining a certain action of the form GYX. We shall now give an example of the form H ´GYX, i.e. a power group action. Afterwards we shall see how these two examples can be combined in order to prove an existence theorem for a certain class of graphs. While doing so we shall meet an interesting and useful counting principle which uses suitable actions of S2, the smallest nontrivial group.
  • Selfcomplementary graphs
  • Involutions
  • The Involution Principle
  • The Principle of Inclusion and Exclusion
  • The Garsia-Milne bijection
  • Exercises

  • harald.fripertinger@kfunigraz.ac.at,
    last changed: August 28, 2001

    Special symmetry classesActionsEnumeration of symmetry classesThe involution principle