In this paper, we prove that the Torelli part of the symplectomorphism groups of the n-point (n ≤ 4) blow-ups of the projective plane is trivial. Consequently, we determine the symplectic mapping class group. It is generated by reflections on Kω-spherical class with zero ω area.
Bibliographical notePublisher Copyright:
© 2015, University of Michigan. All rights reserved.